Is there any particular different between box 1, box 2, box 3? and button, primary button, link button?

Hi, can anybody help to explain, is there any particular different between box 1, box 2, box 3 ? what is the usage of this 3 different box?

and, also button, primary button, and link button.

image

I think Axure is just providing some defaults for basic styling to get you started.