It varies in size and style of mask, but the main difference is the area of your face that is covered.
There are variations in each size and style of mask, but the main differences are what areas of your face are covered. A nasal pillows mask rests at the entrance of your nostrils, a nasal mask covers the nose and a full face mask covers the nose and mouth.
The mask type that best suits you depends greatly on personal needs and preferences. Some things that you may want to take into consideration are your facial anatomy, facial hair, whether or not you're claustrophobic, and if you have any sinus or nasal issues.
Each mask has its own benefits and we recommend you see your Sleep Coach or ResMed Authorised Dealer to try on various mask styles and decide which is best for you.