years vs year dot

years and year dot both are nouns.

Word	Noun	Adjective	Verb	Adverb
years	Yes	No	No	No
year dot	Yes	No	No	No

As nouns, year dot is a hyponym of years; that is, year dot is a word with a more specific, narrower meaning than years:

Other hyponyms of years include month of Sundays, aeon, eon, blue moon.

years (noun)	year dot (noun)
a late time of life	as long ago as anyone can remember
a prolonged period of time
the time during which someone's life continues