words vs soliloquy

words and soliloquy both are nouns.

Word	Noun	Adjective	Verb	Adverb
words	Yes	No	No	No
soliloquy	Yes	No	No	No

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

words: words making up the dialogue of a play
soliloquy: a (usually long) dramatic speech intended to give the illusion of unspoken reflections

Other hyponyms of words include aside, cue, monologue, throwaway.

words (noun)	soliloquy (noun)
words making up the dialogue of a play	speech you make to yourself
an angry dispute	a (usually long) dramatic speech intended to give the illusion of unspoken reflections
the text of a popular song or musical-comedy number
the words that are spoken
language that is spoken or written