Not different at all, just different stages of development. You can't easily recruit hard bodied players to your club via the draft, and it will always take time for them to develop. Essendon are building towards a team similar in make-up to the current Geelong side, adopting the same/very similar gameplan because it suits the list the best.Completely different IMO, every premiership clubs game style becomes the new vogue for clubs, but its rare for clubs to implement it successfully.
Geelong are so good because they've got a great mix of speed, braun and skill. They've got the inside recievers that win the ball out of the centre, the skillful outside players that pinpoint the forwards and the speed off half back that sets up attack from defence.
Essendon don't have the big bodies - which is why they were smashed when they played the Cats, but they do have speed and young players. Bare in mind, Geelong's arsen of players were built up over a 7-8 year period.
Also, since when is 'young players' a game style.