walkway vs boardwalk

walkway and boardwalk both are nouns.

Word	Noun	Adjective	Verb	Adverb
walkway	Yes	No	No	No
boardwalk	Yes	No	No	No

As nouns, boardwalk is a hyponym of walkway; that is, boardwalk is a word with a more specific, narrower meaning than walkway:

Other hyponyms of walkway include ambulatory, catwalk, flagging, mall, promenade, pavement, sidewalk, skywalk.

walkway (noun)	boardwalk (noun)
a path set aside for walking	a walkway made of wooden boards; usually at seaside