github doesn't really serve "end users" for the most part. github is designed for libraries and pieces of open source that will be used by other developers. So the "end users" github services are developers.

SourceForge is designed so that developers can serve their wares to end users. As in, someone with a Windows PC that wants to download a media player.

This difference in use case is one reason that SourceForge's top projects are all apps and github's top projects are all libraries/framerworks for use in development projects.