Studio is the tool where Robots are developed by the RPA Developers. UiPath Studio requires the Development License. Studio is a tool used by the RPA developers and it requires a Development License to work.
Once the robots are developed, you would require an Attended Robot License or an Unattended Robot License for the Robot to perform the activities in the Production Environment.
Orchestrator is a tool which works as a Remote Control to which the Studio and the Robots are connected to. You need to acquire a Server License for the Orchestrator to work.
Studio Deploys the Robots through Orchestrator and the Orchestrator can Control, Monitor and Manage all your Digital Workforce ie Robots performing tens of thousands of automated processes securely from one place.
Hope this is clear!