early-morning hour vs morning

early-morning hour and morning both are nouns.

Word	Noun	Adjective	Verb	Adverb
early-morning hour	Yes	No	No	No
morning	Yes	No	No	No

early-morning hour (noun)	morning (noun)
an hour early in the morning	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