What is difference between CPAP, BiPap and XPAP?

Hi everyone. I am new to this forum. I would really appreciate your advice. I was diagnosed with sleep apnea about 8 years ago, but after a two month try with a BiPap and a mask that slipped around during sleep despite being so tightly strapped to my head that it folded my nose up like an accordion, I gave up. I developed a few permanent nose wrinkles from that mask!

I'd like to give this machinery a try again because I need better sleep! Can someone please tell me what the differences between the machines are, and what is considered top of the line these days? I've read many posts on masks, and realize I will have to try many. Thanks very much for your help!

Just a few letters.

xPAP - any PAP machine
CPAP - one constant pressure (though the C stands for continuous
APAP - Automatically adjusted pressure base on the patients needs
Bi PAP - Bi level machine, which has to level, on for inhaling and one for exhaling.
Click on the CPAPopedia - underneath blue book above the message list for more detailed info.
O.