What do they mean?

PAP = Positive Airway Pressure 
General name for machines that use air pressure to keep your airway open during sleep.

CPAP = Continuous Positive Airway Pressure 
Delivers one steady pressure all night.

APAP = Automatic Positive Airway Pressure 
Automatically adjusts pressure to keep the airway open, eliminating or reducing obstructive sleep apnea

BiPAP / VPAP = Bilevel Positive Airway Pressure
Uses two pressure levels – a higher one when you inhale and a lower one when you exhale.

Auto-VPAP = Automatic Bilevel PAP
A bilevel machine that can also adjust pressures automatically.

ASV = Adaptive Servo-Ventilation 
A specialized machine that adjusts support breath by breath for certain complex breathing patterns.

IMPORTANT NOTE: The right machine and settings should come from a clinician or sleep specialist.