How can you tell if a venomous snake isn't venomous?

Yes, you can. The simple way is to look at the snake. A venomous snake generally has a neck and then the head. The head is usually diamond shaped and you can see where the head and body are different. A non venomous snake has one long line from the body to the head. One reason there is a difference is the poison sacks in the venomous snake create the look of a neck and the head is more pointed than round because of the fangs.