In the development of webpart, we have encountered two types of files.
1. .Dwp and 2. .Webpart.
As you may know, they are both files used for describing where the code is for a web part.
The difference is .dwp was the file extension used in version 2 of SharePoint and .webpart is a new extension used in version 3.
Inside the files, the schemas are different and it is indicated as such by the version number on the xmlns attribute.
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.