So they are both the same form factor (M2) but the data bus they use to communicate with your system is different.
A SATA M2 uses the SATA bus which is capped at 6Gb per second.
A PCIe M2 uses the PCIe bus which is significantly faster. As it's the same bus your GPU uses and much higher bandwidth.
So on paper, this means the PCIe is significantly faster. In application though, 99% of cases the speed difference will be negligible, simply because the rest of system and your software doesn't necessarily utilise the higher speed any more. SATA is already quite fast for most applications. Where you might get some noticeable benefit is in very large data transfer between 2 PCIe drives, or when doing incredibly large data intensive tasks (I believe such as heavy movie making/editing).
Either way, PCIe is usually about the same price as SATA in M2 form factor nowadays, so there is often little reason to opt for the SATA version when it is "technically" faster. But if you happen to get a really good deal on a SATA one, you won't notice the difference between a SATA one and a PCIe one in nearly all applications.
Some boards are only compatible with SATA ones as the M2 slot only uses bandwidth from the SATA bus.
Some board are only compatible with PCIe interface.
Some boards are compatible with both (like yours).