knob vs decoration

knob and decoration both are nouns.

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

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

Other hypernyms of knob include ornament, ornamentation.

knob (noun)	decoration (noun)
a round handle	the act of decorating something (in the hope of making it more attractive)
a circular rounded projection or protuberance	something used to beautify
an ornament in the shape of a ball on the hilt of a sword or dagger	an award for winning a championship or commemorating some other event
any thickened enlargement