Spiders and insects are both arthropods. They have jointed legs. The group of arthropods also includes crustaceans, such as crabs. 

Spiders have eight legs, whereas insects have six legs. 

Spiders are predators. They mainly eat insects. Some spider species weave webs in order to catch flying insects. 

All spiders are capable of biting. Spiders paralyze their prey with poison.