There are two type of SSD connections, SATA and M.2
There are also two types of SSD interfaces, SATA and PCIe (yes I know this is where it gets confusing).
The slowest is to use a SATA drive with a SATA interface.
You can also get an M.2 drive with a SATA interface. there is NO performance advantage, the only advantage is the physical size.
Finally you can get an M.2 drive with a PCIe NVMe interface, this drive has a large performance advantage, however one you barely notice in day to day computing. Its the best one though due to size and speed.
As Rogue Leader has stated...there are virtually no performance differences of any consequence between the two types of SSDs. At least we haven't found any.
The one advantage we've found for a number of laptop/notebook users is that by installing an M.2 SSD in their system it provides the capability of utilizing two internally-connected drives in the system since it frees the HDD drive bay for another 2.5" drive should the user desire such.