The difference between bay and bow windows is simply in the number and angle of panes.
A bay window is typically three glazing areas (but can have more), with the middle window area being the larger ‘picture window’ – they sit at between a 25–45 degree angle.
A bow window is more symmetrical and made up of four or five glazed areas, fitted at a 10 degree angle, giving them a beautiful curved shape, ideal for those panoramic views.
Both bay and bow windows can follow the brick feature of your home, or can simply just protrude from your home.