verse vs octosyllable

verse and octosyllable both are nouns.

Word	Noun	Adjective	Verb	Adverb
verse	Yes	No	Yes	No
octosyllable	Yes	No	No	No

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

verse: a line of metrical text
octosyllable: a verse line having eight syllables or a poem of octosyllabic lines

verse (noun)	octosyllable (noun)
a piece of poetry	a verse line having eight syllables or a poem of octosyllabic lines
a line of metrical text
literature in metrical form

verse (verb)	octosyllable (verb)
familiarize through thorough study or experience
compose verses or put into verse