a whole other ball of wax

a whole other ball of wax

Something very different to, and often more difficult or complicated than, something else. It's one thing to babysit your friends' kids from time to time, but having your own children is a whole other ball of wax. I know you think you're some hotshot just because you worked in television once, but working on a film is a whole other ball of wax.
See also: ball, of, other, wax, whole