What are difference between gum abscess and canker sores. how to identify tooth abscess? what are common symptoms of abscess?

A tender, raised gingival lesion with surrounding erythematous mucosa can be a tooth abscess whereas cancer sore is present as an ulcer like a crater. The pain of acute tooth abscess will be exacerbated with trying to move the tooth but pain from cancer sore is separated from the tooth, only worse when eating. Cancer sore is often on the cheek or tongue, not on the gum.

See a dentist to determine the cause of your lesion.

Please see your Dentist who has successfully been taught both Periodontics, Oral Pathology, and Oral Medicine. Though it would be fun, there isn't enough room here to teach you how to discriminate between the 2 different lesions noted. And whatnyou have may be something else entirely. Self diagnosis is an exercise in futility. Go see someone with appropriate training.