Cold sores do not appear inside your mouth and only appear on the outside of your mouth on the lips, nostrils and chin.
Canker sores are what appears inside your mouth. So if you have a sore that hurts inside your mouth then it's a canker sore.
Canker Sores and Cold sores are different and if the sore is inside your mouth then it's a canker sore.
You can gargle with some apple cider vinegar to get rid of the canker sore inside your mouth or apply some orajel to the canker sore.
Gargling with warm salt water can also help get rid of a canker sore.