Short passes will be aimed, usually, at the nearest player regardless of whether he's infront, to the side or behind the player with the ball. This hopes to keep possession of the ball by not making long, interceptable passes, but short passes to unmarked team mates who can then look for other options. However, this can backfire if there are no options available and can result in quite a lot of possession but no real chances to score.
Direct passing may also pass it to a player nearby, but will nearly always look to go forward. Passes are also more likely to be airbourne. This system looks to get the ball to the forwards to create chances as quickly as possible so as to get more attempts on goal, but obviously there's more chance of the passes being intercepted.