@edgarblythe,
We have a similar thing in the FA Cup.
All finals are held at Wembley, but the semis are held at a neutral ground.
I was going to say the same about play off but I was wrong.
At the end of every season teams are either relegated or promoted to different leagues.
In the premiership the three worst performing sides are relegated to the Championship.
The two top sides in the Championship are automatically promoted to the premiership but the third place is decided in a play off.
The team that comes third plays the that comes sixth two games home and away, and the same is true for the teams who finish fourth and fifth, and the winners meet at Wembley, the winning side is promoted to the premiership and the losing side stays in the championship.