Skunk is a variety, and it's called that because of its distinct smell (it WREAKS, and I love it!). Hash is more potent than bud (HOPEFULLY!), because it's made by rubbing off the trichomes off of the buds. It is then heated and pressed. Basically, it's more pure. You're smoking less plant material, and taking in smoke with higher concentrations of THC! You've probably had weed that smells skunky. It's very distinct, and even an amateur smoker would be able to pick this out. And no, skunk is not necessarily more potent.