radio spectrum vs radio-frequency spectrum

radio spectrum and radio-frequency spectrum both are nouns.

Word	Noun	Adjective	Verb	Adverb
radio spectrum	Yes	No	No	No
radio-frequency spectrum	Yes	No	No	No

As nouns, radio spectrum and radio-frequency spectrum are synonyms defined as:

radio spectrum and radio-frequency spectrum: the entire spectrum of electromagnetic frequencies used for communications; includes frequencies used for radio and radar and television

radio spectrum (noun)	radio-frequency spectrum (noun)
the entire spectrum of electromagnetic frequencies used for communications; includes frequencies used for radio and radar and television	the entire spectrum of electromagnetic frequencies used for communications; includes frequencies used for radio and radar and television