Something I see often missing in drawings is the window niche. Simplification and stylization in art are a more than valid art form, and things don't have to be accurate! But if you want to draw windows more accurate to how they actually are, here is a small breakdown.
(the windows I have drawn in the breakdown are more the german and european windows I know. In the examples on picture 4 you see I've drawn US American windows. The structure is a bit different. But there is a window niche and the frame "hugs" the window from the outside)







