X-radiation vs roentgen ray

X-radiation and roentgen ray both are nouns.

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

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

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

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

X-radiation (noun)	roentgen ray (noun)
obtaining images by the use of X rays	electromagnetic radiation of short wavelength produced when high-speed electrons strike a solid target
electromagnetic radiation of short wavelength produced when high-speed electrons strike a solid target