As the transition keeps moving forward where YSM and adCenter will become a single platform, its imporntant to note the differences and keep everyting running during the transition.

Here are a couple articles to help you get started thinking about the differences and what to do through the transition:

http://searchengineland.com/whats-new-with%C2%A0bing-yahoo-search-alliance-46721
http://searchengineland.com/the-yahoomicrosoft-search-alliance-managing-campaigns-through-the-transition-45230