Cold Sores (Herpes Simplex)
No, they are not the same. Cold sores occur outside of the mouth on the lips or near the mouth and are caused by the herpes simplex virus (HSV-1 or HSV-2). Cold sores are contagious, especially when they are blistered and oozing.
Canker sores, also known as aphthous ulcers, occur inside of the mouth on the tongue, gums, or insides of the cheek. Canker sores are not infectious and as far as we know, cannot be contagious.