Well, when you talk about buttons...
You have the basic Text buttons. Just supply the text and configure the action the button performs. Not much you can influence that way.
You have the Transparent buttons. Again, you supply text and you have some coloring options.
You have the IMAGE buttons. With those, it's all dependent on the image and how it has been configured. There are typically three images involved. One for the regular state, one for the moused over state and one for the clicked state. So whatever you want to be done visually is all part of the image. The up side is that you have infinite ability to customize. The down side is that once you create the image, you can't customize things "on the fly".
And lest I forget, there are Smarty Pants Shapes that can be configured as buttons. (I hear Lilybiri swooning in the background because I said the word "Smart Shape". LOL)
Cheers... Rick