bilevel rail car vs bilevel railcar

bilevel rail car and bilevel railcar both are nouns.

Word	Noun	Adjective	Verb	Adverb
bilevel rail car	Yes	No	No	No
bilevel railcar	Yes	No	No	No

As nouns, bilevel rail car and bilevel railcar are synonyms defined as:

bilevel rail car and bilevel railcar: a type of rail car that has two levels of passenger accommodation, as opposed to one, increasing passenger capacity.

Other synonyms of bilevel rail car include bilevel car, double-deck carriage, double-deck rail car, double-deck railcar.

bilevel rail car (noun)	bilevel railcar (noun)
a type of rail car that has two levels of passenger accommodation, as opposed to one, increasing passenger capacity.	a type of rail car that has two levels of passenger accommodation, as opposed to one, increasing passenger capacity.