sugar vs shortbread
What is the difference between a sugar cookie and a shortbread cookie?
Basically, the proportions are different. Shortbread has a lot more butter. Therefore, it tastes better, but performs differently from sugar cookies. Shortbread cookies are generally crumblier, and also can be harder to decorate (they often need to be double coated with royal icing if you're trying to make, say, decorated christmas cookies).