Electronic pet doors are popular with cat owners and dog owners who are concerned with security. Motorized pet doors operate very much like a garage door. They slide up and down instead of having a push-through flap. These types of automatic doggie doors help to keep unauthorized animals and people from entering or exiting your home.
On the other hand, magnetic dog doors only prevent uninvited "guests" from entering your home, but will not prevent exit. Magnetic doggie doors tend to cost less than electric dog doors. If preventing entry alone covers your concerns a magnetic pet door may be a perfect solution for you.