I'm assuming you applied to OAA...
MPL is the easyjet 'sponsored' course. At the end you'll have an MPL licence. Total cost is about 104,000pounds.
APP is the standard ab-initio course.
I suggest you call Oxford. Depending on your results from day one, you'll probably just be invited back to do day two (interview and team assessment) for the APP. Not sure about for MPL.