cellphone vs wireless telephone

cellphone and wireless telephone both are nouns.

Word	Noun	Adjective	Verb	Adverb
cellphone	Yes	No	No	No
wireless telephone	Yes	No	No	No

As nouns, wireless telephone is a hypernym of cellphone; that is, wireless telephone 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
wireless telephone: a telephone that communicates by radio waves rather than along cables

Other hypernyms of cellphone include radiophone, radiotelephone.

cellphone (noun)	wireless telephone (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