Smoke detectors come in two flavors: ionization and optical. One looks for the ions created by a hot fire; the other looks for smoke from fires. The optical ones work faster on a smoldering fire, the ionization ones work faster on hot fires that give off ions. Either fire type will eventually set off. A heat detector goes off if the heat exceeds the set point, sort of like a thermostat.
Cooking in the kitchen often produces smoke, so that type of detector should be avoided in the kitchen.