What’s the difference between a canker sore and a cold sore?

Canker sores are small, non-contagious mouth ulcers that can form on the gums, tongue, inside of the lips, and inside of the cheek. It’s unclear what causes them, but they tend to occur after a minor injury to the mouth, like accidentally biting your lip, or sensitivity to certain foods, like something spicy or acidic. Minor canker sores go away on their own in a week or so, but bigger ones may take longer. Because canker sores can be irritating and painful, your doctor can prescribe a mouth rinse to reduce inflammation, and you can also purchase over-the-counter topical ointments to soothe the pain.
Cold sores, on the other hand, are sores or blisters that form on the outside border of the lips. Cold sores occur when you contract the herpes simplex virus through close personal contact, like kissing or sharing drinks. Once you have this virus, there is no cure. Cool compresses and possibly antiviral or anti-inflammatory drugs are often prescribed to reduce pain and treat cold sores.
References:
http://www.mayoclinic.org/diseases-conditions/canker-sore/basics/definition/con-20021262
http://www.mayoclinic.org/diseases-conditions/cold-sore/basics/definition/con-20021310