Although not a direct answer to your question, this blog series will help you to understand the difference better :
/people/thomas.weiss/blog/2006/01/24/what-the-new-enhancement-framework-is-for-150-its-basic-structure-and-elements-for-beginners
/people/thomas.weiss/blog/2006/03/15/the-new-enhancement-framework-part-2--what-else-you-need-to-know-before-building-an-enhancement
/people/thomas.weiss/blog/2006/04/03/how-to-define-a-new-badi-within-the-enhancement-framework--part-3-of-the-series
/people/thomas.weiss/blog/2006/04/18/how-to-implement-a-badi-and-how-to-use-a-filter--part-4-of-the-series-on-the-new-enhancement-framework
/people/thomas.weiss/blog/2006/05/03/source-code-enhancements--part-5-of-the-series-on-the-new-enhancement-framework
