If you book through Disney Catered Events, they will not let you have anything wedding-like—no wedding cake, no wearing your bridal attire inside the park—because they want to prevent people from trying to have a Wishes wedding without paying for one. If you book through your Escape planner it will be a 2-hour meal (so your buffet and bar will work) rather than a full-on reception with DJ and dancing (which would have to take place after the park closed anyway). But two hours with fireworks and food will be plenty entertaining!
The only cost difference is that DFTW requires you to pay a $10/guest viewing fee even for guests who have park admission, whereas DCE will only charge you for those without park admission.