commuter vs commuter train

commuter and commuter train both are nouns.

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

As nouns, commuter and commuter train are synonyms defined as:

commuter and commuter train: a passenger train that is ridden primarily by passengers who travel regularly from one place to another

commuter (noun)	commuter train (noun)
a passenger train that is ridden primarily by passengers who travel regularly from one place to another	a passenger train that is ridden primarily by passengers who travel regularly from one place to another
someone who travels regularly from home in a suburb to work in a city