What are the main differences between the 2 Winix models?

The Winix model AUS5500 has 4 stages of air purification: pre-filter, HEPA filter, Carbon filter and PlasmaWave.

The Winix Ultimate model AUS9500 has 5 stages of air purification: pre-filter, HEPA filter, Activated Carbon filter, Anti-bacterial shield and PlasmaWave. This model has extra features such as twin air quality sensors, timer and easy to use ‘set and forget’ options.