gaffer vs linesman

gaffer and linesman both are nouns.

Word	Noun	Adjective	Verb	Adverb
gaffer	Yes	No	No	No
linesman	Yes	No	No	No

As nouns, linesman is a hypernym of gaffer; that is, linesman is a word with a broader meaning than gaffer:

Other hypernyms of gaffer include electrician, lineman.

gaffer (noun)	linesman (noun)
a person who exercises control over workers	a person who installs or repairs electrical or telephone lines
an elderly man	official (in tennis, soccer, football, etc.) who assists the referee in some way (especially by watching for out of bounds or offside)
an electrician responsible for lighting on a movie or tv set