wire for ground/power

Can anyone tell me if the wires used for the power and ground of an amp are the same type of wire? in other words, can I buy one spool of wire and use it for both power and ground?

Yes you can use the same wire for both.  The only real difference in the wire is the color.  If you are confident that this will not cause a wiring issue in the future you can use the same color wire.  If you want to know the difference between the wires but use the same wire you can wrap tap around the ground as an indicator or which wire is what.

Yea the wire is the exact same stuff, just different colors used for reference.