roentgen ray vs X ray

roentgen ray and X ray both are nouns.

Word	Noun	Adjective	Verb	Adverb
roentgen ray	Yes	No	No	No
X ray	Yes	No	No	No

As nouns, roentgen ray and X ray are synonyms defined as:

roentgen ray and X ray: electromagnetic radiation of short wavelength produced when high-speed electrons strike a solid target

Other synonyms of roentgen ray include X-radiation, X-ray.

roentgen ray (noun)	X ray (noun)
electromagnetic radiation of short wavelength produced when high-speed electrons strike a solid target	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