ESB was a great deal more dynamic in general (some might even say 'showy') - a lot more moving camera and close-up work, often with longer lenses.
As you say, it's a different story and it makes sense to shoot in a different style - I like the visual evolution (at least as far as the first two films go - RotJ heads back towards the wide and static approach). Of course Lucas wasn't overly enamoured with the rushes...