carriageway vs roadway

carriageway and roadway both are nouns.

Word	Noun	Adjective	Verb	Adverb
carriageway	Yes	No	No	No
roadway	Yes	No	No	No

As nouns, roadway is a hypernym of carriageway; that is, roadway is a word with a broader meaning than carriageway:

carriageway: one of the two sides of a motorway where traffic travels in one direction only usually in two or three lanes
roadway: a road (especially that part of a road) over which vehicles travel

carriageway (noun)	roadway (noun)
one of the two sides of a motorway where traffic travels in one direction only usually in two or three lanes	a road (especially that part of a road) over which vehicles travel