reek vs give off

reek is a noun but give off is not a noun.

Word	Noun	Adjective	Verb	Adverb
reek	Yes	No	Yes	No
give off	No	No	Yes	No

As verbs, give off is a hypernym of reek; that is, give off is a word with a broader meaning than reek:

reek: give off smoke, fumes, warm vapour, steam, etc.
give off: give off, send forth, or discharge; as of light, heat, or radiation, vapor, etc.

Other hypernyms of reek include emit, give out.

reek (noun)	give off (noun)
a distinctive odor that is offensively unpleasant

reek (verb)	give off (verb)
be wet with sweat or blood, as of one's face	have as a by-product
smell badly and offensively	give off, send forth, or discharge; as of light, heat, or radiation, vapor, etc.
have an element suggestive (of something)
give off smoke, fumes, warm vapour, steam, etc.