If you are talking about people, 'pretty' is used mainly for girls and young women. 'Good-looking' is used more to describe boys and men, and maybe older women.

Better don't use pretty for a man! But you can say: he is pretty good looking! (joke: pretty here means "fairly, rather, or quite")

'Pretty' is often seen as a feminine word. Similar words (depending on the situation) could be 'attractive' or 'delicate' 'That dress is pretty' 'That flower was pretty' A guy would probably not appreciate being called pretty 'Good-looking' is gender-neutral. You can say both "A good-looking guy" and "A good-looking girl" however people will more often say "A pretty girl" Hope this helped!

"pretty" is a little bit good looking, whereas "good-looking" is quite pretty. [Just a joke, Su.Ki's answer is spot on.]