Question:
Does anyone have an idea what sort of sensors fire alarms are supposed to have in different countries, or in different types of buildings, etc.? Do most fire alarm systems found in (any kind) of building detect smoke or heat?

Is the type of sensor which is used dependent on some sort of legal requirement? Is there a global organization determining some sort of fire safety code?

Answer: Besides smoke detectors, there is a device called a "rate of rise" detector. You can use this outside or in a garage where car exhaust would set off a smoke detector. Basically if the temperature gets hot real fast, it will trip. If the temperature rises slowly like outside in Arizona where it will reach 120, it will not trip. Also if it gets very hot, it will trip.

Also there are just heat sensors. These trip when the temperature reaches a certain amount.

Then there are special smoke detectors which are placed in air conditioning air handlers in large buildings.

Then there are water flow sensors for fire water sprinklers.

Some fire alarms shut down the main electrical feed to a building when the fire alarm trips.

Then ionization and photo electric smoke detectors. Some smoke detectors have both smoke and heat detection.

Large building fire alarms also have "trouble" detection. This would be anything which could keep the fire system from working. For example if someone shut off the water to the fire sprinkler system, you would get a "trouble" alarm.