JD will make some nerdy jokes in his head and sometimes say them out loud. If you're lucky sometimes a black joke here and there. And if there is some celebrity guest on the show at the time he'll hook up with her.
The Janitor will get up to some wacky antics trying to annoy someone.
Elliot will lack confidence and talk about how she was called (insert name) in highschool, later on gaining confidence only for it to reset the next episode.
Dr Cox will have at least one insanely long monologue about what annoys him.
Ted will always be a loser/suicidal and every episode will cement this further
Seriously you don't have to watch this show consistently at all to get it, it will just help fill in some of the blanks story wise, but it's nothing like AD. I loved the first season of scrubs because it was fast paced and original, but the last 3 seasons were pretty dull IMO. The show seemed to rise again during the last half of season 4 so I'll download this and see.