decorate vs ornament

decorate is not a noun while ornament is a noun.

Word	Noun	Adjective	Verb	Adverb
decorate	No	No	Yes	No
ornament	Yes	No	Yes	No

As verbs, decorate and ornament are synonyms defined as:

decorate and ornament: make more attractive by adding ornament, colour, etc.

Other synonyms of decorate include adorn, beautify, embellish, grace.

As verbs, ornament is a hyponym of decorate; that is, ornament is a word with a more specific, narrower meaning than decorate:

decorate (noun)	ornament (noun)
	something used to beautify

decorate (verb)	ornament (verb)
provide with decoration	make more attractive by adding ornament, colour, etc.
make more attractive by adding ornament, colour, etc.	be an ornament to
award a mark of honor, such as a medal, to
be beautiful to look at