X ray vs X-radiation

X ray and X-radiation both are nouns.

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

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

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

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

X ray (noun)	X-radiation (noun)
a radiogram made by exposing photographic film to X rays; used in medical diagnosis	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