What makes a cassette mountain bike vs. road bike? I'm in the market for a new cassette for my road bike and I frequently see cassettes listed as mountain bike or road bike. Since they're usually interchangeable and can be used on either type of bike, what makes manufacturers designate them as one type or the other?
Road typically has a smaller range.  A road bike will typically come with a short cage derailleur.  Where a mountain will typically come with a medium or long cage derailleur.   Yes the mount on the freehub is compatible.  It is about the range capacity of the derailleur.