Ultrasonic and evaporative
Ultrasonic units create a fine mist; evaporative designs move air through or over wet media. Their refill and consumable routines differ, so compare more than the presence of a visible plume.
Warm mist and installed systems
Warm-mist units heat water. Installed whole-home humidifiers depend on the building system and its controls. Installation and maintenance requirements deserve a separate review from portable appliances.
Read the exact manual
Product names can use hybrid or cool mist in different ways. Verify the underlying method on the official product page and in the manual for that model.