mobile phone vs radiotelephone

mobile phone and radiotelephone both are nouns.

Word	Noun	Adjective	Verb	Adverb
mobile phone	Yes	No	No	No
radiotelephone	Yes	No	No	No

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

mobile phone: 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 mobile phone include radiophone, wireless telephone.

mobile phone (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