SATA 3 vs M.2 Pros and Cons?

it your mobo support pcie type m.2 sure. get the m.2

Go for the M2 in a laptop

m.2 NEW fast lightweight pricy
sata is legacy HDD drive size standard. Cheapper. Open the ssh case find 1/3 of the space filled with air. most drives on sata already look like this:
https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcR7DV7Lgr5D--61jcTdY5r49wqowkfmgjoPgwtsrEytiQsWFQB7
exclude 1 TB drives and higher.

get m.2 as os fast drive and HDD for storage. this is best combo.

"M.2" is simply the form factor. How it connects.

M.2 drives can be either SATA or NVMe.
The 970 EVO you link is an NVMe drive. Those are the faster ones. And significantly more expensive per GB.

There are SATA M.2 drives. Same price and performance as a traditional 2.5" SATA III drive. Just a different plug in.

For instance, "m.2" drives.
SATA
Crucial MX500 - 500GB - $110
https://www.amazon.com/Crucial-MX500-500GB-2280SS-Internal/dp/B077SQ8J1V

Samsung 970 EVO - 250GB - $108
https://www.amazon.com/Samsung-970-EVO-250GB-MZ-V7E250BW/dp/B07BN5FJZQ

Same $$, twice the size.

Why doesn't everyone have an NVMe drive? $$$ vs actual usage.
Not every system or user would benefit from the speed of the NVMe. My wife's system and use case would not see any difference over the 250GB 850 EVO in that system now.

Also, not everyone's system can actually use an NVMe drive. My current main system is an ASRock Z97M - i7 4790k.
I'd have to build a whole new system to take full advantage of that 970 EVO drive you linked.

And the 970 EVO NVMe vs the 860 PRO you compared is a false choice.
You need to look at the price difference between the 970 EVO and the 860 EVO. Big difference.

They are not "way faster". They're slightly faster - you probably won't be able to tell the difference between the two in real-life use outside of a few esoteric use cases.

The problem is the benchmarks are all done in MB/s. Humans don't think in MB/s. They think in terms of how long they have to wait for the computer to complete an operation. That's wait time or sec/MB - the inverse of MB/s. When you measure theses SSD speeds on sec/MB, the huge MB/s increases end up making a very small difference. Imagine you need to copy 1 GB of sequential data.

125 MB/s HDD = 8 sec
250 MB/s SATA 2 SSD = 4 sec
500 MB/s SATA 3 SSD = 2 sec
1 GB/s PCIe SSD = 1 sec
2 GB/s NVMe SSD = 0.5 sec

Notice how every time MB/s doubles, the amount of wait time reduction is only half the previous step? So the huge 1000 MB/s speed increases we're at now translate into only tiny fractions of a second reduction in wait time. The biggest wait time reduction was from moving from a HDD to a SATA SSD. The increased "huge" MB/s speed increases of M.2 SSDs translate into only a tiny reduction in wait time. If you call the speed increase from a HDD to a 3 GB/s latest-gen NVMe SSD 100%, then:

250 MB/s SATA 2 SSD = 4 sec wait time reduction = 52%
500 MB/s SATA 3 SSD = 6 sec wait time reduction = 78%
1 GB/s PCIe SSD = 7 sec wait time reduction = 91%
2 GB/s NVMe SSD = 7.5 sec wait time reduction = 98%
3 GB/s NVMe SSD = 7.67 sec wait time reduction = 100%

So basically, the SATA 3 SSD gives you 80% the wait time reduction of the fastest M.2 SSDs. You're probably not going to notice the 20% difference between it and the M.2 drive, but the M.2 drive is probably going to cost you about 50%-100% more.

Also, because MB/s is the inverse of what's important, the smallest MB/s figure actually ends up being most important. Say you wanted to copy 1 GB of sequential data and 200 MB of 4k data. Say you're comparing the 970 EVO NVMe SSD with 3 GB/s sequential read speeds and 33 Mb/s 4k read speeds, vs the SATA 860 Pro with 550 MB/s sequential read speeds and 50 MB/s 4k read speeds. Which will be faster?

If you think in MB/s, you see 3 GB/s vs 550 MB/s - the 970 EVO is nearly 6x faster. 50 MB/s vs 33 MB/s - the 860 Pro is only 1.5x faster. And you're copying 5x as much sequential data (where the 970 EVO is 6x faster) as you are 4k data (where the 860 Pro is only 1.5x faster). This should be an easy win for the 970 EVO right? Let's crunch the numbers.

970 EVO = (1 GB / 3 GB/s) + (200 MB / 33 MB/s) = 0.33 sec + 6 sec = 6.33 sec
860 Pro = (1 GB / 550 MB/s) + (200 MB / 50 MB/s) = 1.81 sec + 4 sec = 5.81 sec

Surprise! The 860 Pro ends up faster because it's the smallest MB/s benchmark which makes the biggest difference in terms of wait time. Notice how both drives spend far more time on the 4k read than they do the sequential read. Basically, unless you're constantly copying large files between NVMe SSDs, or constantly reading large sequential files (e.g. real-time video editing), you should ignore the sequential speed benchmarks. Compare drives based on their slowest benchmarks - the 4k speeds. That's the one which makes the biggest difference in real-world use. Because of its faster 4k speeds, the 860 Pro will be faster in most real-world tasks despite it being a SATA drive.

It's that pesky inverse. It means smaller is bigger, and bigger is smaller.

It really depends on the use-case. As mentioned already, M.2 is just another form factor like 2.5", 3.5", etc. The faster versions of M.2 are called NVMe which is where the performance boost comes into it. The other M.2 drives are still SATA, their only advantage over a 2.5" SATA SSD comes in that they connect directly to the motherboard, don't require separate cables, and don't take up a drive bay if you want loads of storage.

Now, as far as speaking to the difference between SATA SSD and NVMe SSD, it's really only that noticeable if you regularly move massive amounts of data around, for everything else you're paying a premium for a very similar performance.

Make sure it supports the size specifications too. Does it fit a 2280(22mm x 80mm)?
I'm also about to buy an m.2 for my laptop(it came with a slot and no drive), and am wondering if these are the best options available.

WD Black(2018)
500GB - $200
Up to 3,400 MB/s Read
Up to 2,500 MB/s Write
Up to 410,000 IOPS Read
Up to 330,000 IOPS Write
300TBW

Samsung 970 EVO
500GB- $200
Up to 3,400MB/s Read
Up to 2,300MB/s Write
Up to 370K IOPS Read
Up to 450K IOPS Write
300TBW

Samsung 970 PRO
500GB - $230
Up to 3,500MB/s Read
Up to 2,300MB/s Write
Up to 370K IOPS Read
Up to 500k IOPS Write
600TBW

These specs are directly from the Samsung and WDC websites, so I am pretty sure they are correct.
From what it says, I'm leaning towards the Samsung 970 pro for the double lifetime. Although I doubt I will burn through it when upgrading, considering my 830 is only at 60TBW at 5 years old. Are there any other options in similar price rangers($230 or less)?