mammogram vs X-ray

mammogram and X-ray both are nouns.

Word	Noun	Adjective	Verb	Adverb
mammogram	Yes	No	No	No
X-ray	Yes	No	No	No

As nouns, X-ray is a hypernym of mammogram; that is, X-ray is a word with a broader meaning than mammogram:

mammogram: X-ray film of the soft tissue of the breast
X-ray: a radiogram made by exposing photographic film to X rays; used in medical diagnosis

Other hypernyms of mammogram include roentgenogram, X-ray photograph, X-ray picture, X ray.

mammogram (noun)	X-ray (noun)
X-ray film of the soft tissue of the breast	a radiogram made by exposing photographic film to X rays; used in medical diagnosis
	electromagnetic radiation of short wavelength produced when high-speed electrons strike a solid target