Here is an overview:
http://www.econlib.org/library/Enc1/NeoclassicalEconomics.html
In short, neoclassical economics is the reigning orthodoxy. It centers around modeling as a method of understanding the world. Its major divisions are micro and macro. Macroeconomics does include both Monetarist and Keynesian models. It should be pointed out, however, that there are other Keynesian views which are considered unorthodox.
