Just use Google or Youtube... This isn't some secret information, this is widely known among EV enthusiasts. Even reviews that weigh the car will illustrate the different sized packs - the 50kwh cars are of course lighter too. EV fans obsess over the cell form factor and battery chemistry much like combustion car fans know the internals of car engines. Tesla's own presentation videos (also on youtube) talk endlessly about the new battery cell form factors they've introduced too and which products they are applied to.