oral cancer vs carcinoma

oral cancer and carcinoma both are nouns.

Word	Noun	Adjective	Verb	Adverb
oral cancer	Yes	No	No	No
carcinoma	Yes	No	No	No

As nouns, carcinoma is a hypernym of oral cancer; that is, carcinoma is a word with a broader meaning than oral cancer:

oral cancer: malignant neoplasm of the lips of mouth; most common in men over the age of 60
carcinoma: any malignant tumor derived from epithelial tissue; one of the four major types of cancer

oral cancer (noun)	carcinoma (noun)
malignant neoplasm of the lips of mouth; most common in men over the age of 60	any malignant tumor derived from epithelial tissue; one of the four major types of cancer