Many computers have both SSD's and HDD's in them. Usually, you will see the operating system and programs installed on the SSD because of the speed of access. Then the HDD will be more of a storage drive for pictures and other data because the cost of a multiple TB drive is so low. Those both will be AHCI though. If you are asking about AHCI and NVMe, the interfaces are different. You might be able to run an NVMe drive in AHCI mode, but you would be defeating the purpose. -@bozz