smartphone vs iPhone

smartphone and iPhone both are nouns.

Word	Noun	Adjective	Verb	Adverb
smartphone	Yes	No	No	No
iPhone	Yes	No	No	No

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

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

smartphone (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.