What is the difference between a Pterosaur and a bird?

There are far too many differences to list, but here are a few major ones. Pterodactylus was a pterosaur, eagles are birds. Pterodactylus was partially covered in hair-like pycnofibers, eagles are almost completely covered in feathers. Pterodactylus had a long neck, long jaws, and lots of tiny teeth, while eagles have a short neck, a short, curved beak, and no teeth. Pterodactylus would have killed its prey with its teeth, while eagles kill their prey with their talons. Pterodactylus walked on all fours, while eagles walk on two feet.