HELP LAW PEOPLE! What is the difference between a "prosecuting attorney" and a "deputy prosecutor"?

It probably makes no difference at all. From the attorney's prospective one may have been paid more than the other. But your choice of defense attorney should include other factors including length of time as an attorney, number of trials, extent of office support, paralegals and back-up staff, etc. You can not really judge by rate of "success" since that is a rather elusive criterion and is itself subject to a multitude of factors.