Native slotting into server drive cages. No concerns about alignment with the front or back.

There was a jump between old early gen SATA SSDs and modern NVMe in my opinion, but it’s really only noticable if you’re running something like a game with a huge amount of data to load, and you’re actively comparing the two.

My old PC had several different hard drives of differing types and I’d periodically be too lazy to move a game from one drive to another so I’d play it off different drives over a period of time, and was able to compare the loading times.

So I’d say they’re faster, but it’s nowhere near the leap that HDD to SSD was.