smart phone vs iPhone

smart phone and iPhone both are nouns.

Word	Noun	Adjective	Verb	Adverb
smart phone	Yes	No	No	No
iPhone	Yes	No	No	No

As nouns, iPhone is a hyponym of smart phone; that is, iPhone is a word with a more specific, narrower meaning than smart phone:

smart phone: a mobile phone with more advanced computing capability and connectivity than basic feature phones
iPhone: a smartphone designed and marketed by Apple Inc.

smart phone (noun)	iPhone (noun)
a mobile phone with more advanced computing capability and connectivity than basic feature phones	a smartphone designed and marketed by Apple Inc.