walker vs traveller

walker and traveller both are nouns.

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

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

Other hypernyms of walker include traveler.

walker (noun)	traveller (noun)
an enclosing framework on casters or wheels; helps babies learn to walk	a person who changes location
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