What does this last scene ultimately show us about the relationship between Andrew Neyman and Terence Fletcher?

Watch the movie Whiplash (2014).What do you make of the last 10 minutes of the film, which focus on Andrew Neyman as he plays an intense drum solo of the song “Caravan” in front of an audience, with Terence Fletcher leading? What does this last scene ultimately show us about the relationship between Andrew Neyman and Terence Fletcher?