old-timer vs gaffer

old-timer and gaffer both are nouns.

Word	Noun	Adjective	Verb	Adverb
old-timer	Yes	No	No	No
gaffer	Yes	No	No	No

As nouns, old-timer and gaffer are synonyms defined as:

Other synonyms of old-timer include antique, old geezer, oldtimer.

old-timer (noun)	gaffer (noun)
an elderly man	a person who exercises control over workers
an experienced person who has been through many battles; someone who has given long service	an elderly man
	an electrician responsible for lighting on a movie or tv set