morn vs period of time

morn and period of time both are nouns.

Word	Noun	Adjective	Verb	Adverb
morn	Yes	No	No	No
period of time	Yes	No	No	No

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

Other hypernyms of morn include period, time period.

morn (noun)	period of time (noun)
the time period between dawn and noon	an amount of time