Canker sore vs cancer, although both manifest as mouth lesions, differ significantly. Canker sores, common and non-contagious, are small ulcers inside the mouth that heal within a week or two. They are often painful and can result from various factors like stress or hormonal changes. In contrast, oral cancer lesions do not heal on their own, may appear as discolored lumps or sores, and are generally painless. Read more!