smartphone vs mobile phone

smartphone and mobile phone both are nouns.

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

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

smartphone: a mobile phone with more advanced computing capability and connectivity than basic feature phones
mobile phone: a hand-held mobile radiotelephone for use in an area divided into small sections, each with its own short-range transmitter/receiver

Other hypernyms of smartphone include cell, cellphone, cellular phone, cellular telephone.

smartphone (noun)	mobile phone (noun)
a mobile phone with more advanced computing capability and connectivity than basic feature phones	a hand-held mobile radiotelephone for use in an area divided into small sections, each with its own short-range transmitter/receiver