Here's a nice article comparing yoga and Pilates...
http://www.citizensvoice.com/site/news.cfm?BRD=2259&dept_id=457355&newsid=14707031&PAG=461&rfi=9
Some folks will get into quite the rant-and-rave session with me over which is better. Or, more likely, why their chosen discipline is the ONLY way anybody should EVER exercise.
Dedicated yogis will struggle with the breathing differences and really not care for the Pilates methods of breathing.
And some folks understand the benefits of both and want to do both. Pilates experts have one school of thought and yoga instructors another.
Personally, I like to live in REALITY which is why my signature classes include a blend of both (or "fusion," the more popular term). If you can exercise four-five hours a week instead of eight, then you have a half-day to yourself! Time is time and there's only so much of it, so I say get the absolute most from every single exercise session.
Angela