bilevel railcar vs bilevel rail car

bilevel railcar and bilevel rail car both are nouns.

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

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

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

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

bilevel railcar (noun)	bilevel rail car (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.