gestation vs gestation period

gestation and gestation period both are nouns.

Word	Noun	Adjective	Verb	Adverb
gestation	Yes	No	No	No
gestation period	Yes	No	No	No

As nouns, gestation and gestation period are synonyms defined as:

gestation and gestation period: the period during which an embryo develops (about 266 days in humans)

gestation (noun)	gestation period (noun)
the conception and development of an idea or plan	the period during which an embryo develops (about 266 days in humans)
the state of being pregnant; the period from conception to birth when a woman carries a developing fetus in her uterus
the period during which an embryo develops (about 266 days in humans)