There are so many similarities between boas and pythons. There are small boas and large pythons. Small Boa Large python There are small pythons and large boas. Small pythons Large boa They are both constricting snakes. There is a possibility that at least 1 boa or python is venomous. They both have triangular heads just like most venomous snakes. So how can you tell if a snake is a boa or a python?