Translation:They have completely different personalities.
i think 'ganska' instead of 'helt' would be more appropriate if you want to use quite.
I guess in that context it sounds kind of sarcastic (ex: 'Are grapes and grapefruits the same thing?' 'No they're quite different' or 'I wouldn't quite call it true love'). Normally, however, I think 'quite' is pretty subtle (ex 'Its quite warm in here' or 'It tastes quite like strawberries.'