cellphone vs cellular phone

cellphone and cellular phone both are nouns.

Word	Noun	Adjective	Verb	Adverb
cellphone	Yes	No	No	No
cellular phone	Yes	No	No	No

As nouns, cellphone and cellular phone are synonyms defined as:

cellphone and cellular phone: a hand-held mobile radiotelephone for use in an area divided into small sections, each with its own short-range transmitter/receiver

Other synonyms of cellphone include cell, cellular telephone, mobile phone.

cellphone (noun)	cellular phone (noun)
a hand-held mobile radiotelephone for use in an area divided into small sections, each with its own short-range transmitter/receiver	a hand-held mobile radiotelephone for use in an area divided into small sections, each with its own short-range transmitter/receiver