occupation vs period of time

occupation and period of time both are nouns.

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

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

occupation: the period of time during which a place or position or nation is occupied
period of time: an amount of time

Other hypernyms of occupation include period, time period.

occupation (noun)	period of time (noun)
the principal activity in your life that you do to earn money	an amount of time
the act of occupying or taking possession of a building
the control of a country by military forces of a foreign power
any activity that occupies a person's attention
the period of time during which a place or position or nation is occupied