What is the difference between a bunny slope and a black diamond slope at a mountain?

Well, this really all depends on your level of experience. When beginning, the runs marked with a green circle are the way to go, followed by the blue squares once you are feeling comfortable. The black diamonds are for expert skiiers/snowboarders, and are usually very steep, with hazards such as large poles (from chairlifts, etc.), trees, and so on in that nature. So, I recommend using much caution and thought when deciding if the black diamond is for you. If you do choose it however, I strongly recommend following a friend/teacher/mentor who has gone down the run (or just knows what to expect). It's fun to ski with a friend, and they will be setting an appropriate pace. :)