devolution vs devolvement

devolution and devolvement both are nouns.

Word	Noun	Adjective	Verb	Adverb
devolution	Yes	No	No	No
devolvement	Yes	No	No	No

As nouns, devolution and devolvement are synonyms defined as:

devolution and devolvement: the delegation of authority (especially from a central to a regional government)

devolution (noun)	devolvement (noun)
the delegation of authority (especially from a central to a regional government)	the delegation of authority (especially from a central to a regional government)
the process of declining from a higher to a lower level of effective power or vitality or essential quality