gaffer vs old man

gaffer and old man both are nouns.

Word	Noun	Adjective	Verb	Adverb
gaffer	Yes	No	No	No
old man	Yes	No	No	No

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

Other hypernyms of gaffer include graybeard, greybeard, Methuselah.

gaffer (noun)	old man (noun)
a person who exercises control over workers	an informal term for your father
an elderly man	a man who is very old
an electrician responsible for lighting on a movie or tv set	a familiar term of address for a man
	(slang) boss
	aromatic herb of temperate Eurasia and North Africa having a bitter taste used in making the liqueur absinthe