There are two basic types of smoke alarms for the

             average home:  Ionization and photoelectric. Ionization

             alarms are much more common.  Ionization alarms are

             much more common. Ionization alarms sound more

             quickly when flaming, fast moving fire occurs. Photoelectric

             alarms are quicker at  sensing smoldering, smoky fire with

             no flames. There are in general it is better to have an

             ionization alarm in your home if you are only going to

             have one type. USFA recommends that both types be

             installed. Photoelectric may be better in kitchens and

             other areas of the home where frequent ionization alarm

             activation is common.