Bay and bow windows look similar but have a few notable differences:

• A bay window has three panels projecting outside the home: a fixed panoramic centre window parallel the wall and two smaller angled panels on either side. Fixed, casement or hung windows may be used for these.
• A bow window generally consists of four or five panels. As the name suggests, these panels form a bow shape. While the centre panels of a bow window are fixed, people often opt for operable side windows, with casement and hung windows being popular choices.

While bay windows typically project further out, both types help expand a space, create a sense of depth and maximize light.