MSI are one of many manufacturers of Nvidia based graphics cards. Nvidia make the graphics processing unit and then MSI fit it to a PCB and add the ancillary hardware. Most, if not all, nvidia cards will show up as Nvidia hardware.
As to the overclocking software it depends on how old the software is. If you had a much older card and never updated the software then it is possible that it simply does not know what your card is. Try updating to the latest MSI Afterburner software and see if that achieves what you want.