harvest time vs time of year

harvest time and time of year both are nouns.

Word	Noun	Adjective	Verb	Adverb
harvest time	Yes	No	No	No
time of year	Yes	No	No	No

As nouns, time of year is a hypernym of harvest time; that is, time of year is a word with a broader meaning than harvest time:

harvest time: the season for gathering crops
time of year: one of the natural periods into which the year is divided by the equinoxes and solstices or atmospheric conditions

Other hypernyms of harvest time include season.

harvest time (noun)	time of year (noun)
the season for gathering crops	one of the natural periods into which the year is divided by the equinoxes and solstices or atmospheric conditions