There are two types of snakes: venomous snakes and constrictors. Venomous snakes bite their victims and the venom from their fangs causes tissue to suffer in one way or another, often causing fatality.
However, if you ingest venom it is usually harmless! The venoms affects the body by attacked the bloodstream and tissue of the victim. Other poisons attack the digestive system. Venom, though, is broken down in your stomach just like other foods.