What are the snakes, their similarities and differences?

Snakes are divided into three groups. The first group is poisonous snakes. They release powerful toxins that paralyze or kill the victim in a very short period of time. They can use poison as a way of catching prey or as a way of defense. The second group is boas. They have no poisons and use suffocation techniques to kill the victim. The third group is already-like snakes. They are practically harmless to humans and many pets. What snakes have in common is their body shape, type of diet, and body structure.