Difference Between .dwp and .webpart

1. 1. Dwp was the file extension used in version 2 of SharePoint and .webpart is a new extension used in version 3
   2. Version number on the xmlns attribute is different [2->2003, 3-> 2007]
   3. The main difference is that all properties passed to the web part are specified with a property element and a name attribute in version 3. Version 2 uses different element names for everything.