Oil question: Compressor vs Air Tool Oil?

I'm a new air owner and am confused by one thing (so far):

Is there a difference between "Compressor Oil" and Air Tool Oil? I thought I was buying the later when I re-read the bottle and found out it was the former. Can Compressor oil be used as air tool oil or is there some property that makes it different, like viscosity or additives? I don't know if I need to return the compressor oil to the store....

Thanks for your help!