Cuz one is hdd the other ssdYou can move the game from one HDD to another so I would guess you can move it from one PC to another, but why not just put your HDD from your old PC into your new one?
thnxYes, you can download and install GTA V on a new PC and it'll work without problems. Some games do have strict DRM with install limits but even those usually allow more than one installation, GTA V doesn't have that problem anyway though.