Difference in body types

Hello all,
Can anyone explain to me the different body styles? And why is one called the j-body and another called the H-body? Are there more body styles?

Thanks,
Tom

Frame/unibody platform. The Oldsmobile Alero is a N-body. Alero, Grand Am, and Malibu are all N-body cars.

also the only type of body kits i could find for an alero would be the Razzi as you all know and the Kato Combat kits.

there is the AED kit also....