locomotive engineer vs railroad engineer

locomotive engineer and railroad engineer both are nouns.

Word	Noun	Adjective	Verb	Adverb
locomotive engineer	Yes	No	No	No
railroad engineer	Yes	No	No	No

As nouns, locomotive engineer and railroad engineer are synonyms defined as:

locomotive engineer and railroad engineer: the operator of a railway locomotive

Other synonyms of locomotive engineer include engine driver, engineer.

locomotive engineer (noun)	railroad engineer (noun)
the operator of a railway locomotive	the operator of a railway locomotive