refine vs improve

refine and improve both are verbs.

Word	Noun	Adjective	Verb	Adverb
refine	No	No	Yes	No
improve	No	No	Yes	No

As verbs, improve is a hypernym of refine; that is, improve is a word with a broader meaning than refine:

Other hypernyms of refine include ameliorate, amend, better, meliorate.

refine (verb)	improve (verb)
reduce to a fine, unmixed, or pure state; separate from extraneous matter or cleanse from impurities	get better
improve or perfect by pruning or polishing	to make better
treat or prepare so as to put in a usable condition
attenuate or reduce in vigor, strength, or intensity by polishing or purifying
make more precise or increase the discriminatory powers of
make more complex, intricate, or richer