break of the day vs morning

break of the day and morning both are nouns.

Word	Noun	Adjective	Verb	Adverb
break of the day	Yes	No	No	No
morning	Yes	No	No	No

As nouns, break of the day and morning are synonyms defined as:

Other synonyms of break of the day include aurora, break of day, cockcrow, dawn, dawning, daybreak, dayspring, first light, sunrise, sunup.

break of the day (noun)	morning (noun)
the first light of day	a conventional expression of greeting or farewell, used to wish someone a good morning
	the earliest period
	the time period between dawn and noon
	the first light of day