commuter vs straphanger

commuter and straphanger both are nouns.

Word	Noun	Adjective	Verb	Adverb
commuter	Yes	No	No	No
straphanger	Yes	No	No	No

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

commuter: someone who travels regularly from home in a suburb to work in a city
straphanger: a commuter who uses public transportation

commuter (noun)	straphanger (noun)
a passenger train that is ridden primarily by passengers who travel regularly from one place to another	a standing subway or bus passenger who grips a hanging strap for support
someone who travels regularly from home in a suburb to work in a city	a commuter who uses public transportation