the difference is midway between 2 windows which are about 6 feet apart. no cabinets will be hung here, maybe a hutch will set there. I have a 9-1/2" lambeam above. I put a strait edge from one window to the next, then I put the 4x4 which the beam sets on out to the straight edge. I shimmed the studs on one side and shaved the studs on the other. I also shaved the top and bottom plates on the one side. It's not perfectly straight, but it looks pretty good.