How much does the Enterprise increase/vary in size between models?

In the show Enterprise, it's mentioned the ship has a complement of about 80 and you also see some of the Makos sharing quarters in season 3 (although they are not part of the normal crew so it's not clear if this is the norm).

In TNG I think I recall that the ship has about 400 crew (and TOS somewhere in between) and family on board. Yet the ships look pretty similar so I wondered do the ships really get much larger or is it just one of those details which don't tie up across the Star Trek universe - like how the Enterprise ship looks far more like the TNG one than the TOS one even though it's more primitive.