AHCI and RAID are different animals; however, I would expect that RAID drivers tend to use as much of the AHCI features as possible.
I'm not sure how it works now, but some years ago mobo makers caused confusion on these points. Some provided drivers for AHCI devices and RAID devices separately, and that was clear. You only set the SATA Port Mode to RAID if you actually were using RAID arrays. But others combined the two drivers into one, so you HAD to set the port mode to RAID to use that driver, even if you were NOT using RAID.
These days, however, the drivers for AHCI devices are "built in" in Windows Vista and up, so there is no need to install such drivers separately. Thus, there ought not to be any unified AHCI / RAID driver, and no need at all to install a RAID driver unless you are using a RAID array. That should mean that you ONLY install a RAID driver and set the port mode to RAID if you really ARE using a RAID array. Otherwise, set it to AHCI.