The setup with jobs and positions and how they were connected was confusing when I first started working with Dynamics 365 for Talent, hope this makes it cleare for you!
A job is a collection of tasks and responsibilities.
Positions is an individual instance of a job. You can have several positions connected to one job.
You can’t have more then one job connected to one position
The job is CRM consultant, the position is CRM consultant in Oslo which is assigned to me. A worker can be connected to one ore more positions, but they can’t be connected to a job.
You can’t create a position and connect it to a worker before you have created the job. Only the position is organized in a hierarchy.