What is the difference between a photoelectric and ionization smoke alarm?

This is a good question. A photoelectric smoke alarm is one where a light source is focused on the sensory chamber. As smoke enters the chamber, it causes the light to be reflected. This triggers the alarm. This is the best smoke alarm option when detecting large smoke particles from slow and smouldering fires.

The ionization smoke alarm has a minimal amount of radioactive material that is located on two plates. The plates have an electrical charge that is ionized. When smoke enters the chamber, that ionized flow is disrupted, and the alarm begins to sound. This is the ideal smoke alarm for fast-moving or small smoke particles.