What are the differences and similarities of the pterodactyl and brontosaurus?

I'm not a paleontologist but I'm a dino freak and my understanding is that Teradactyl "meaning: winged finger" were larger and had teeth. Pteranadon "meaning: wing without teeth" were smaller and did not have teeth. Some think that Pteranadon's are later versions of the Teradactyl and became more streamlined and lost there teeth through evolution.

A bit of trivia: These were some of the first fliers and had incredibly thin skeletons and would have been inanely clumsy on the ground. Also there necks were very frail and they were no taller than 5 or 6 feet. Contrary to Jurassic Park III, a human could kill one of these with little effort!