arthrogram vs roentgenogram

arthrogram and roentgenogram both are nouns.

Word	Noun	Adjective	Verb	Adverb
arthrogram	Yes	No	No	No
roentgenogram	Yes	No	No	No

As nouns, roentgenogram is a hypernym of arthrogram; that is, roentgenogram is a word with a broader meaning than arthrogram:

arthrogram: an X ray of a joint after the injection of a contrast medium
roentgenogram: a radiogram made by exposing photographic film to X rays; used in medical diagnosis

Other hypernyms of arthrogram include X-ray, X-ray photograph, X-ray picture, X ray.

arthrogram (noun)	roentgenogram (noun)
an X ray of a joint after the injection of a contrast medium	a radiogram made by exposing photographic film to X rays; used in medical diagnosis