There's a slight difference. Revise is more to edit or look through something again. To modify is to change or update. Revise is more commonly used when talking about writing, whereas modify is more commonly used with technology. Revision is fixing problems; modifying is usually adding on or adapting.

there is no difference, revise and modify are synonyms. that means that those two words mean the same thing, it's just a different way of saying it. i wish i could explain it better but my thoughts can't be put into words. if that didn't make sense to you, please let me know so i can explain further! :-)