call it a day vs cease

call it a day is not a noun while cease is a noun.

Word	Noun	Adjective	Verb	Adverb
call it a day	No	No	Yes	No
cease	Yes	No	Yes	No

As verbs, cease is a hypernym of call it a day; that is, cease is a word with a broader meaning than call it a day:

Other hypernyms of call it a day include discontinue, give up, lay off, quit, stop.

call it a day (noun)	cease (noun)
	(`cease' is a noun only in the phrase `without cease') end

call it a day (verb)	cease (verb)
stop doing what one is doing	put an end to a state or an activity
	have an end, in a temporal, spatial, or quantitative sense; either spatial or metaphorical