customise vs modify

customise and modify both are verbs.

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

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

Other hypernyms of customise include alter, change, build, construct, make.

customise (verb)	modify (verb)
make according to requirements	make less severe or harsh or extreme
make to specifications	add a modifier to a constituent
	cause to change; make different; cause a transformation