garland vs decorate

garland is a noun but decorate is not a noun.

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

As verbs, decorate is a hypernym of garland; that is, decorate is a word with a broader meaning than garland:

Other hypernyms of garland include adorn, beautify, embellish, grace, ornament.

garland (noun)	decorate (noun)
flower arrangement consisting of a circular band of foliage or flowers for ornamental purposes
an anthology of short literary pieces and poems and ballads etc.

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