The primary difference between a Master of Philosophy (M.Phil.) over a regular Doctoral course is that the former is a degree over the Ph.D. (Doctor of Philosophy). Different universities conduct the M.Phil. degree differently, so you should have a conversation with a faculty member or administrator before making any final decisions.

It is, in general, an intermediate degree, to connect the way to the PhD course. Many schools that award the MPhil degree admit graduate students for that degree and then invite the outstanding performers into a Ph.D. programme.