prehistory vs period of time

prehistory and period of time both are nouns.

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

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

prehistory: the time during the development of human culture before the appearance of the written word
period of time: an amount of time

Other hypernyms of prehistory include period, time period.

prehistory (noun)	period of time (noun)
the time during the development of human culture before the appearance of the written word	an amount of time