gradation vs graduation

gradation and graduation both are nouns.

Word	Noun	Adjective	Verb	Adverb
gradation	Yes	No	No	No
graduation	Yes	No	No	No

As nouns, gradation and graduation are synonyms defined as:

gradation (noun)	graduation (noun)
the act of arranging in grades	the act of arranging in grades
a degree of ablaut	the successful completion of a program of study
relative position in a graded series	a line (as on a vessel or ruler) that marks a measurement
	an academic exercise in which diplomas are conferred