water of crystallisation vs water of hydration

water of crystallisation and water of hydration both are nouns.

Word	Noun	Adjective	Verb	Adverb
water of crystallisation	Yes	No	No	No
water of hydration	Yes	No	No	No

As nouns, water of crystallisation and water of hydration are synonyms defined as:

water of crystallisation and water of hydration: the water present in hydrated compounds

Other synonyms of water of crystallisation include water of crystallization.

water of crystallisation (noun)	water of hydration (noun)
the water present in hydrated compounds	the water present in hydrated compounds