A dome skylight angles up towards the outside of the roof. A flat skylight is much like a regular window. Both of these skylight perform the same basic function: to allow light to come in through the roof and keep out the elements. The big difference between them is and how they look. Some people prefer to have a flat skylight that does not grab your attention. Other people like to have the dome skylight because of the unique look that it provides. Both types are durable and will help protect your home from the elements while allowing light in.