"The moral of the finale: Twilight Sparkle is better than her friends.
Celestia said she had all of the things that make them special (generousity, loyalty, kindness, etc). She has all of the things that make the individual races special (flying, earth connection, and unicorn magic). She is taller than them (she only slightly shorter tahn Cadance height now). And lastly, Celestia said that her friends are now her students, and they bow to her as her subjects."