cellphone vs radiotelephone

cellphone and radiotelephone both are nouns.

Word	Noun	Adjective	Verb	Adverb
cellphone	Yes	No	No	No
radiotelephone	Yes	No	No	No

As nouns, radiotelephone is a hypernym of cellphone; that is, radiotelephone is a word with a broader meaning than cellphone:

cellphone: a hand-held mobile radiotelephone for use in an area divided into small sections, each with its own short-range transmitter/receiver
radiotelephone: a telephone that communicates by radio waves rather than along cables

Other hypernyms of cellphone include radiophone, wireless telephone.

cellphone (noun)	radiotelephone (noun)
a hand-held mobile radiotelephone for use in an area divided into small sections, each with its own short-range transmitter/receiver	a telephone that communicates by radio waves rather than along cables
	telephony that uses transmission by radio rather than by wire