Aside from a label or different color, from the outside, the BiPAP machine may not look significantly different from a CPAP.

They deliver air through a mask. Continuous positive airway pressure devices treat moderate to severe obstructive sleep apnea. They give you constant air pressure to keep your breathing passages ...

CPAP and BiPAP (Bilevel Positive Airway Pressure ... "This therapy involves wearing a mask connected to a machine that delivers a constant, steady stream of air at a fixed pressure.