phlebogram vs roentgenogram

phlebogram and roentgenogram both are nouns.

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

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

phlebogram: an X ray of a vein injected with a radiopaque contrast medium
roentgenogram: a radiogram made by exposing photographic film to X rays; used in medical diagnosis

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

phlebogram (noun)	roentgenogram (noun)
an X ray of a vein injected with a radiopaque contrast medium	a radiogram made by exposing photographic film to X rays; used in medical diagnosis