ornamentation vs decoration

ornamentation and decoration both are nouns.

Word	Noun	Adjective	Verb	Adverb
ornamentation	Yes	No	No	No
decoration	Yes	No	No	No

As nouns, decoration is a hypernym of ornamentation; that is, decoration is a word with a broader meaning than ornamentation:

ornamentation: the act of adding extraneous decorations to something
decoration: the act of decorating something (in the hope of making it more attractive)

As nouns, ornamentation and decoration are synonyms defined as:

Other synonyms of ornamentation include ornament.

ornamentation (noun)	decoration (noun)
the act of adding extraneous decorations to something	the act of decorating something (in the hope of making it more attractive)
something used to beautify	something used to beautify
the state of being ornamented	an award for winning a championship or commemorating some other event