The main difference between HEPA and ionizer air purifiers is their method of cleaning the air:
HEPA (High Efficiency Particulate Air) purifiers use a dense filter to physically trap particles like dust, pollen, and smoke as air passes through.
Ionizer purifiers use electrical charges to ionize air molecules, causing particles to become attracted to collector plates where they can be trapped.
HEPA filters are better at removing smaller particulates down to 0.3 microns, while ionizers are more effective on larger particles and some gaseous pollutants. Many purifiers combine both HEPA filtration and ionization for maximum cleaning capability.