Christmas vs season

Christmas and season both are nouns.

Word	Noun	Adjective	Verb	Adverb
Christmas	Yes	No	No	No
season	Yes	No	Yes	No

As nouns, season is a hypernym of Christmas; that is, season is a word with a broader meaning than Christmas:

Christmas (noun)	season (noun)
a Christian holiday celebrating the birth of Christ; a quarter day in England, Wales, and Ireland	one of the natural periods into which the year is divided by the equinoxes and solstices or atmospheric conditions
period extending from Dec. 24 to Jan. 6	a recurrent time marked by major holidays
	a period of the year marked by special events or activities in some field

Christmas (verb)	season (verb)
	make healthy
	make more temperate, acceptable, or suitable by adding something else
	lend flavor to