Thank you thank you everyone - so helpful! You are correct that we are removing a wall and the windows unfortunately are not identical. They are the same style and both start at the same point at the top, but one of them is a couple of inches longer than the other. How bad will that look? I imagine removing a window is quite costly and would prefer to avoid that if we can.

What is your exterior? Would it be easy to patch? Get more siding, faces neighbors so you don't see a potantial mis-match? Could you either replace smaller window to match larger or as I believe has been suggested, make them into one larger window? This may give enough siding material to make a patch that can't be detected.