To begin with it's SATA vs m2 SSD. M.2 SSD is connected to the motherboard directly via a PCI-E slot and thus can be faster than the sata, which has a limit of 6gb (current generation). Thing is most SSDs right now are not fast enough to use all the speed provided by the SATA. So for most SSDs SATA is enough, however it is good when you buy a new motherboard to look into M2 slot so that you can upgrade to M2 SSD in the future when faster SSDs come out.