There are many different brands of smoke alarms available on the market but they fall under two basic types: ionization and photoelectric.
Ionization alarms sound more quickly when a flaming, fast moving fire occurs.Photoelectric alarms are quicker at sensing smoldering, smoky fires. There are also combination smoke alarms that combine ionization and photoelectric into one unit, called dual sensor smoke alarms.
Because both ionization and photoelectric smoke alarms are better at detecting distinctly different yet potentially fatal fires, and because homeowners cannot predict what type of fire might start in a home, the USFA recommends the installation of both ionization and photoelectric or dual sensor smoke alarms.
In addition to the basic types of alarms, there are alarms made to meet the needs of people with hearing disabilities. These alarms may use strobe lights that flash and/or vibrate to assist in alerting those who are unable to hear standard smoke alarms when they sound.