refrain vs keep off

refrain is a noun but keep off is not a noun.

Word	Noun	Adjective	Verb	Adverb
refrain	Yes	No	Yes	No
keep off	No	No	Yes	No

As verbs, keep off is a hyponym of refrain; that is, keep off is a word with a more specific, narrower meaning than refrain:

Other hyponyms of refrain include fast, fast, avoid, teetotal.

refrain (noun)	keep off (noun)
the part of a song where a soloist is joined by a group of singers

refrain (verb)	keep off (verb)
choose not to consume	refrain from entering or walking onto
resist doing something	refrain from certain foods or beverages