What is the Difference Between SATA and SSD and HDD and NVMe?

If you are new to buying storage devices, particularly solid state drives (SSDs), then the first thing you’ll notice is that you are bombarded with technical terms such SATA, NVMe, PCIe, 2.5, M.2, HDD, SSD and what not.

Hence, for the uninitiated, it can get very difficult to buy the right storage. I often get emails asking me about whether a certain SSD or HDD will work with their system. I also get unfortunate emails where people have bought an SSD stick only to find out that there system does not fully support it.

So how you navigate around all the technical jargon? What is the difference between SATA and SSD and HDD and NVMe and all other terms under the sun?

Basically, you need to understand that there are two interfaces for storage devices. SATA is a storage device interface, so is PCIe NVMe. SSD and HDD, on the other hand are storage technologies.

The terms 3.5″, 2.5″ and M.2 relate to the form factor or the physical dimension of the storage drive.

In the following text, I will talk in detail about all the technical jargon involved with the storage drives

So What is the Difference Between SATA and SSD and HDD and NVMe etc?

While related, these terms and acronyms pertain to completely different specs of a hard drive. 

Compare SATA vs SSD is like comparing a hard drive storage compacity vs its physical size. While they are both related to hard drive, they are completely different specs and would naturally be read separately.

Essentially, you need to compartmentalize the technical jargon for hard drive terms of their classification.

  1. SATA and PCIe NVMe are Interfaces
  2. HDD and SSD are Storage Technologies
  3. 3.5″, 2.5″ and M.2 are Form Factors

SATA vs PCIe NVMe – The Two Interfaces Used for Storage Devices

For starters, know that storage devices are based around two interfaces: SATA and PCIe NVMe.

SATA Interface

Which is Faster SATA or PCIe
SATA Ports

SATA storage drives use the SATA ports on your motherboard to connect to your PC.

SATA is the most popular interface for connecting storage drives. The average spinning hard disk drives (HDDs) found on desktops and laptops use the SATA interface.

hard drive ports connections
3.5″ HDD found on desktops use the SATA interface

There are different versions of the SATA interface. The most current version is SATA 3 and it has max transfer rate of 6 Gbps or 750 MB/s.

You can find both HDDs AND SSDs that utilize the SATA interface.

Also Read: Do You Need an HDD and SSD Both on Your PC?

PCIe Interface

PCIe, on the other, is much superior interface for connecting storage drives. At the moment, it is gaining more and more popularity and will replace SATA interface in the near future as the current trend goes.

PCIe interface is SOLELY intended for a special class of solid state drives called NVMe SSDs. More on this below. But understand that PCIe SSDs and NVMe SSDs are the same.

There are NO PCIe NVMe based hard disk drives (HDDs).

PCIe is basically the interface that the special NVMe communication protocol uses for compatible SSDs.

A PCIe NVMe essentially makes use of the PCIe lanes. A typical PCIe NVMe connects to FOUR PCIe lanes. The speed of each PCIe lanes depends upon what version of the PCIe interface the motherboard and the CPU conforms to.

The following table shows how the speed of the PCIe lanes doubles with every new generation:

Versionx1
(GB/s)
x2
(GB/s)
x4
(GB/s)
x8
(GB/s)
x16
(GB/s)
1.00.2500.500 1.0002.0004.000
2.00.5001.0002.0004.0008.000
3.00.9851.9693.9387.87715.754
4.01.9693.9387.87715.75431.508
5.03.9387.87715.75431.50863.015
6.07.87715.75431.50863.015126.031

This has a huge impact on performance of the PCIe NVMe SSDs:

A Gen 3 NVMe SSD conforming to PCIe 3.0 can reach speeds of 3500 MB/s. A Gen 4 NVMe SSD conforming to PCIe 4.0 can reach speeds of 6500 MB/s!

M.2 Slot Length
A typical M.2 slot with the different lengths marked. A PCIe NVMe goes into an M.2 slot.

PCIe NVMe SSDs connect to M.2 slots on your motherboard. The M.2 slot MUST support the right version of the PCIe interface in order to fully support your PCIe NVMe SSD.

Also Read:

SSD vs HDD – Storage Technologies

Hard Disk Drives (HDDs) and Solid State Drives (SSDs) are basically storage technologies.

Hard Disk Drives:

Hard Disk Drives (HDDs) use the spinning disks for storage and a vast majority of the PCs out there have an HDD.

What is the Difference Between SATA and SSD and HDD and NVMe
3.5″ Hard Disk Drive with Spinning Disks/Platters

So essentially, hard disk drives are mechanical in nature. The head moves around the disks in order to read or write data physically on the platters of the desk.

Hard disk drives are highly limited by their mechanical nature and are thus very slow in transferring data.

The best of the best HDDs can give you a maximum of 150-200 MB/s transfer speed. You can see that HDDs do not even saturate the speed of the interface they connect to (i.e SATA 3 = 750 MB/s).

While they are slow, their biggest advantage is their price and capacity. Hence, they are great for archiving data. HDDs are cheap (almost 1/4th the cost of SSDs).

HDDs use SATA interface.

Solid State Drives 

Solid State Drives (SSDs), on the other hand, make use of electronic circuits to store data. Hence, SSDs have no moving parts. 

As such, SSDs are far superior in speed as compared to HDDs. SSDs can reach speeds of upto 6500 MB/s! (depending upon type, make and model)

SSDs can use both SATA OR PCIe NVMe Interface.

The following table explains the difference further:

  HDD SSD
Technology Mechanical Electronic
Speed Very Slow (200 MB/s Max) Super Fast (Upto 6500 MB/s)*
Interface SATA SATA, PCIe NVMe
Cost 1/4th the cost of NVMe SSDs per GB Expensive
Form Factor 3.5″, 2.5″ 2.5″ and M.2
Capacity Huge Capacities Low Capacity
  • *SATA SSDs are slower than PCIe NVMe SSDs; PCIe NVMe SSDs can reach speeds of upto 6500 MB/s depending upon the make and model

Also Read: How Many SATA Drives Can I Connect?

Form Factor of the Storage Drives: 3.5″ 2.5″ and M.2

The final piece of the puzzle in understanding storage drives is the form factor.

Storage drives can have 3.5″, 2.5″ or M.2 form factor.

3.5″ Hard Disk Drives

Can You Use a Laptop Hard Drive in a Desktop hard disk
A 3.5″ SATA Hard Disk Drive. AKA Desktop HDD.

The 3.5″ form factor is reserved only for Hard Disk Drives (HDDs). These are generally known as desktop HDDs.

3.5″ form factor gets its name from the diameter of the spinning disks inside the HDD.

3.5″ HDDs use the SATA interface.

2.5″ Hard Disks Drives AND Solid State Drives

What Are SATA Cables Used For
2.5″ Laptop HDD. Source: Wikimedia

The 2.5″ is a small form factor generally used by laptop HDDs. It also gets its name from the diameter of the spinning disks.

However, you can also find the 2.5″ form factor used by certain SSDs such as the one shown below:

SATA SSD
2.5″ SATA SSD

It should be noted that both the 2.5″ HDDs and 2.5″ SSDs use the SATA interface.

While 2.5″ HDDs have a speed of about 100 MB/s. The SATA 2.5″ SSDs can reach speeds of about 550 MB/s if connected to SATA 3 port on your motherboard.

Read in Detail: What is SATA 2.5?

M.2 Form Factor: Used by SATA and PCIe NVMe SSDs

Finally we have the M.2 form factor. This form factor is solely used by SSDs – Both SATA and PCIe NVMe.

M.2 SSDs plug into M.2 slots on your motherboard.

M.2 Slot Length
A typical M.2 slot with the different lengths marked. A PCIe NVMe goes into an M.2 slot.

Again, let me reiterate as this point is very important to note. Both SATA and PCIe NVMe SSD can be found using the M.2 form factor.

Take for instance the Samsung 860 SSD below. This is a SATA SSD that uses the M.2 form factor.

Samsung Evo 860 SATA SSD m.2
Samsung Evo 860 SATA SSD with M.2 form factor

Similarly take for instance the Samsung 980 Pro below. This is a PCIe NVMe SSD that uses the M.2 form factor. It conforms to PCIe v4.0 aka Gen 4 NVMe SSD.

samsung 980 pro
Samsung 980 Pro. M.2 PCIe 4.0 NVMe SSD

Of course, you need to have the right M.2 port in order to facilitate the right SSD and its generation

Read in Detail: How to Tell if My M.2 Slot is NVMe or SATA?

Understanding the Keys on M.2 SSDs

Take note that while SATA and NVMe SSDs can both use the M.2 form factor, they have different keys that can help you identify which one is which.

m2 sata key
(Left) M.2 NVMe SSD uses the M Key; (Right) M.2 SATA SSD uses B+M Key. Source: atpinc.com

The key refers to the notches and their position on the M.2 SSD connectors.

  • B Key is used by NVMe SSD; offers 2 PCIe Lanes – not really used now days.
  • M Key is used by NVMe SSDs; offers 4 PCIe Lanes
  • B+M Key is used by SATA SSDs typically.
To Summarize

Summary and What It All Boils Down To…

So given all the information, the following are all they types of drives you can find:

Storage Type
Read Speeds
3.5″ SATA HDD  ~120-200 MB/s (Max)
2.5″ SATA HDD ~80-160 MB/s (Max)
2.5″ SATA SSD ~550 MB/s (Max)
M.2 SATA SSD ~550 MB/s (Max)
M.2 Gen 3 PCIe NVMe SSD ~3500 MB/s (Max)
M.2 Gen 4 PCIe NVMe SSD ~7000 MB/s (Max)
  • The speeds above are the maximum achievable. The actual speed depends upon the make and model the drive.

Also Read: How to Add More M.2 SSD Slots?

FAQ

NVMe vs SSD – What is the Difference?

NVMe is a communication protocol and NVMe SSDs are a type of SSD. 

NVMe SSDs are basically SSDs that use the PCIe interface and the NVMe communication protocol.

SSD, on the other hand, is a storage technology. These are different from typical hard disk drives (HDDs) as they do not have any moving parts and much faster in comparison.

Essentially, you should know that there are two types of SSDs: NVMe SSDs and SATA SSDs.

NVMe SSDs, as stated earlier, use the PCIe interface and are the fastest drives out there. SATA SSDs, on the other hand use the SATA interface. They are slower in comparison to NVMe SSDs but are faster compared to typical HDDs.

Are SATA Drives Faster Than SSD?

People often ask this question however it premises if incorrect.

While most SATA drives are HDDs, SATA drives can also be SSDs. SATA is an interface whereas SSD is a type of storage technology. SATA SSDs are much faster as compared to SATA HDDs.

However, PCIe NVMe SSDs are even faster than SATA SSDs. Hence the idea goes:

PCIe NVMe SSD > SATA SSD > HDD

Are SSD and SATA the Same Thing?

No, they are not.

SSD is a storage technology and SATA is an interface that an SSD uses to connect to your PC.

Also Read: How Many Hard Drives Can a PC Have?

What is Better PCIe SSD or SATA SSD?

PCIe NVMe SSDs are a lot better than SATA SSDs.

The latest SATA 3 SSDs have a maximum transfer rate of 550 MB/s at best.

PCIe SSDs (depending upon what generation of PCIe they conform to) can reach transfer speed of 6500 MB/s. 

Are NVMe and SATA Compatible?

If you have an M.2 slot capable of supporting an NVMe SSD, there is a high possibility that it will also support a SATA M.2 SSD.

However, if you have an M.2 slot that support ONLY SATA SSDs, then it will not be able to support the NVMe SSDs.

Read in Detail: How to Tell if My M.2 Slot is NVMe or SATA?

Final Words

Storage drives can get very confusing particularly if you are trying to understand what is the difference between SATA and SSD and HDD and the rest of the confusing acronyms and technical jargon.

I have tried my best to simply the terms enough for an average consumer. If you have any questions you can always comment down below.

You can also explore this site further, perhaps you will find the answer you are looking for.

 

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Author:

Atif Qazi
Atif Qazi is the founder of PCGuide101. He is a digital nomad who loves everything PC. He is a PC builder, tech enthusiast, engineer, and a lover of single player lore-rich RPG games.

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