Translation:Please return the money by tomorrow.
「まで」is a point of the time,place,something has done or something is happning. And it sounds continous action.
「明日まで宿題をやろう」＝Let's do homewok until tomorrow.
「５時まで開いている」＝It's open until 5:00.
「までに」doesn't use for a place. is a point of a particular time,something has done or something is happning, and basicaly use for "has to do or has to be".It sounds like a dead line.
「明日までに宿題をやろう」＝Let's finish the homework by tomorrow.
「８時までに行かなくていけない」＝I must go there by 8:00.
「５時までには開いている」＝It should be open by 5:00.
yup; that is the correct distinction.