harden vs modify

harden and modify both are verbs.

Word	Noun	Adjective	Verb	Adverb
harden	No	No	Yes	No
modify	No	No	Yes	No

As verbs, modify is a hypernym of harden; that is, modify is a word with a broader meaning than harden:

harden (verb)	modify (verb)
become hard or harder	make less severe or harsh or extreme
make hard or harder	add a modifier to a constituent
make healthy	cause to change; make different; cause a transformation
cause to accept or become hardened to; habituate
harden by reheating and cooling in oil