cancer vs carcinoma

cancer and carcinoma both are nouns.

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

As nouns, carcinoma is a hyponym of cancer; that is, carcinoma is a word with a more specific, narrower meaning than cancer:

cancer: any malignant growth or tumor caused by abnormal and uncontrolled cell division; it may spread to other parts of the body through the lymphatic system or the blood stream
carcinoma: any malignant tumor derived from epithelial tissue; one of the four major types of cancer

Other hyponyms of cancer include lymphoma, cancer of the blood, leucaemia, leukaemia, leukemia, sarcoma.

cancer (noun)	carcinoma (noun)
any malignant growth or tumor caused by abnormal and uncontrolled cell division; it may spread to other parts of the body through the lymphatic system or the blood stream	any malignant tumor derived from epithelial tissue; one of the four major types of cancer