They mean more or less the same and are mosty used in the same way. Ex: "han tok omkring henne" and "Han tok rundt henne" has the same meaning. However, in this specific example, you would not say "her rundt?", but "rundt her?" (I can't explain exactly why, just sounds better)
Some of the vowels sound a lot a like. I'm using this page http://www.learn-norwegian.net/pronunciation/pronunciation.htm#current to learn how to say the vowels.