undo vs modify

undo and modify both are verbs.

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

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

Other hypernyms of undo include alter, change.

undo (verb)	modify (verb)
cancel, annul, or reverse an action or its effect	make less severe or harsh or extreme
cause to become loose	add a modifier to a constituent
remove the outer cover or wrapping of	cause to change; make different; cause a transformation
deprive of certain characteristics
cause the ruin or downfall of