M.2 Keying

Ok, I'm begging somebody to explain the difference to me in the various M.2/NGFF keying. I've bought 3 m.2 to SATA adapters, but none of them will fit any of the standard M.2 SSDs that I have. I've scoured the internet in search of why, and understand that there are SATA and PCIe (NVMe) variants, which will have different lanes, but from everything I've read, the M.2 physical interface should be the same across the board. I can tell you, it's not. Could somebody please shed some light on this?

 

Well M.2 replaces Sata in speed does it not?
But the bottlenecks are.......did someone say KFC?