old hand vs old-timer

old hand and old-timer both are nouns.

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

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

old hand and old-timer: an experienced person who has been through many battles; someone who has given long service

Other synonyms of old hand include old stager, oldtimer, stager, veteran, warhorse.

old hand (noun)	old-timer (noun)
an experienced person who has been through many battles; someone who has given long service	an elderly man
	an experienced person who has been through many battles; someone who has given long service