Fever blisters

The term ‘fever blister’ is just another name for the cold sore virus caused by the herpes simplex virus-1. A fever blister is a small facial lesion that appears on or adjacent to the lips. Early signs of a fever blister are redness, burning, and tingling of the skin. Treatment should be administered as soon as the first signs become apparent.

Lip sores

Lip sores are sores or ulcers on the lips. The most common kind is a cold sore.
Cold sores are often refered to as ‘lip sores’, however this is not really correct, as there are several causes of lip sore, not directly associated with the cold sore virus. These include: canker sores, candidiasis, behcet's disease and chancre. However these are just a few of the possible causes of lip sore, and there will be others that are not mentioned here. It would be advisable to seek help from your doctor, to confirm the source and cause of the lip sore.