Whats the difference between a cold sore and canker sore?

Cold sore vs canker: Neither one is a medical terminology. Both are often used interchangeably as they are used by non-medical professionals. A cold sore usually involves lips, and is caused by herpes simplex virus type 1. A canker sore in medicine is called aphthous stomatitis, which usually involves tongue or inside the gum. We don't know what causes it, but it often happens again and again, triggered by stress.

Same: These are layman's terms for the same thing. They are caused by a virus (typically a herpes virus) and are contagious. So if you have one, do not kiss/have intimate contact or share glasses/utensils, etc with others. And don't kiss/have intimate contact or share glasses or utensils with anyone else who has a cold sore.