Prince Lightning Da Cute

Alright.

Rainbow Dash is cruel and puts innocent cute animals in brutal competitions.

Trixie does not.

Rainbow Dash lacks some self confidence when the pressure is put on her and goes through a psychotic breakdown.

When the pressure is on Trixie, she still trys instead of going insane.

Shall I go on?

But ultimately, Trixie is a show off and a bully. She doesn't allow anyone to share the spotlight with her because she is greedy, and if she were proven wrong in any way/shape/form, she would either continue on blathering about how she is great and mighty when in reality she isn't, or run away like a coward instead of admitting her faults.

you both have great points and faults. Trixie and Rainbow's personality's could be better either way.