words vs bust-up

words and bust-up both are nouns.

Word	Noun	Adjective	Verb	Adverb
words	Yes	No	No	No
bust-up	Yes	No	No	No

As nouns, bust-up is a hyponym of words; that is, bust-up is a word with a more specific, narrower meaning than words:

Other hyponyms of words include affray, altercation, fracas, bicker, bickering, fuss, pettifoggery, spat, squabble, tiff.

words (noun)	bust-up (noun)
words making up the dialogue of a play	a serious quarrel (especially one that ends a friendship)
an angry dispute
the text of a popular song or musical-comedy number
the words that are spoken
language that is spoken or written