sidewalk vs walkway

sidewalk and walkway both are nouns.

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

As nouns, walkway is a hypernym of sidewalk; that is, walkway is a word with a broader meaning than sidewalk:

sidewalk: walk consisting of a paved area for pedestrians; usually beside a street or roadway
walkway: a path set aside for walking

Other hypernyms of sidewalk include paseo, walk.

sidewalk (noun)	walkway (noun)
walk consisting of a paved area for pedestrians; usually beside a street or roadway	a path set aside for walking