radiation therapy vs radiotherapy

radiation therapy and radiotherapy both are nouns.

Word	Noun	Adjective	Verb	Adverb
radiation therapy	Yes	No	No	No
radiotherapy	Yes	No	No	No

As nouns, radiation therapy and radiotherapy are synonyms defined as:

radiation therapy and radiotherapy: (medicine) the treatment of disease (especially cancer) by exposure to a radioactive substance

Other synonyms of radiation therapy include actinotherapy, irradiation, radiation.

radiation therapy (noun)	radiotherapy (noun)
(medicine) the treatment of disease (especially cancer) by exposure to a radioactive substance	(medicine) the treatment of disease (especially cancer) by exposure to a radioactive substance