To gain an understanding of the differences in microevolution and macroevolution, you will need to read the following pages on the Berkeley Evolution 101 site:
- Defining microevolution
- Detecting microevolutionary change
- Mechanisms of microevolution
- What is macroevolution
- Patterns in macroevolution
The Brightstorm video, Microevolution - Macroevolution, gives a good basic explanation of the differences.