Two different TEAMS clients start with Windows

Good morning, I need your help. Two versions of Teams have recently been launched on our Windows clients. How do I get the problem under control and which version is the right one? One version obviously has more functions and offers icons such as Booking, Administration, OneDrive and Calls in the left menu bar. The other version only has Activity, Community, Chat and Calendar. What went wrong?

Thank you in advance for your support and best regards
Alexander Schmidt