skin cancer vs carcinoma

skin cancer and carcinoma both are nouns.

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

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

skin cancer: a malignant neoplasm of the skin
carcinoma: any malignant tumor derived from epithelial tissue; one of the four major types of cancer

skin cancer (noun)	carcinoma (noun)
a malignant neoplasm of the skin	any malignant tumor derived from epithelial tissue; one of the four major types of cancer