The difference between Teeth/Fangs and Claws
	
	
		I have been researching Teeth and claws a bit... 
And have come to find that both can be envenomed. 
Some claws (centipedes and spiders) are right at the mouth area. 
So my question 1: 
What is the difference? Is it merely a matter of location: Fangs are Inside the mouth of the animal and claws are anything outside that region.. . 
And even if that is the case, if someone found a fang like/claw like piece of an animal. 
How do they distinguish between the two? 
Question 2: 
Is there a branch of zoology that focuses on the study of Fangs/claws (especially envenomed verity)? I would like to follow up on this research.