The reports found in My Reports and Shared Reports are all reports which have been created in Report Builder.
The reports displayed in the My Reports sub-menu are reports you have created yourself. You can run, export, print, edit, copy, and delete reports in this area.
The reports displayed in the Shared Reports sub-menu are reports that have been created by other administrators and have been shared with you. You can run, export, print, and copy reports in this area. You cannot edit or delete reports that have been shared with you.