glacial period vs ice age

glacial period and ice age both are nouns.

Word	Noun	Adjective	Verb	Adverb
glacial period	Yes	No	No	No
ice age	Yes	No	No	No

As nouns, glacial period and ice age are synonyms defined as:

glacial period and ice age: any period of time during which glaciers covered a large part of the earth's surface

Other synonyms of glacial period include glacial epoch.

glacial period (noun)	ice age (noun)
any period of time during which glaciers covered a large part of the earth's surface	any period of time during which glaciers covered a large part of the earth's surface