Expanding on the M.2 thing... What's said here is correct that it's a form factor. Probably more than you need to know, but M.2 slots are effectively miniaturized PCI-e slots which means they're capable of a lot of bandwidth. One thing to note though is that they also make SATA drives that work in M.2 slots. If you want to get the full PCI-e speeds (and it's a noticable difference) you will want an NVME drive. Drives that use NVME are much faster than their SATA counterparts, but also hurt the budget more. NVME is the protocol that the drive uses and doesn't have much to do with what shape the drive is. NVME drives can look like memory sticks with the pins on the end (M.2 form factor), they can look like PCI-e cards (and will plug into a normal 4x/8x/16x PCI-e slot), or they can look like normal small form factor (laptop drive size) drives and use a U.2 connector (slightly more obscure than the other two).
tldr: M.2 does not grantee you're getting better speed than SATA. Make sure your drive and motherboard both support NVME if that's what you're going for.
tldr: M.2 does not grantee you're getting better speed than SATA. Make sure your drive and motherboard both support NVME if that's what you're going for.