Bounds vs. Rectangle

What is the difference between Bounds and Rect?

I have read the API, so I see the obvious differences. More specifically:

• Which is better for performance?

• Are Bounds just a 3D Rect?

• When should I use one over the other?

• Anything else to help clarify the difference that you know would be great as well :)

Here is the extent of my knowledge regarding the two: Bounds and Rect.