hiker vs walker

hiker and walker both are nouns.

Word	Noun	Adjective	Verb	Adverb
hiker	Yes	No	No	No
walker	Yes	No	No	No

As nouns, walker is a hypernym of hiker; that is, walker is a word with a broader meaning than hiker:

Other hypernyms of hiker include footer, pedestrian.

hiker (noun)	walker (noun)
a foot traveler; someone who goes on an extended walk (for pleasure)	an enclosing framework on casters or wheels; helps babies learn to walk
	a light enclosing framework (trade name Zimmer) with rubber castors or wheels and handles; helps invalids or the handicapped or the aged to walk
	a shoe designed for comfortable walking
	a person who travels by foot