The difference being that byu is actually a team that is, you know, located South of the Utes so it makes sense. Also, it was good trash talk that had momentum.
The little brother thing obviously makes no sense to anyone but the 94' Aerostar minivan drivin, MLM schemin, White short sleeve dress shirt wearin mega zoobs. I've never heard someone say it besides Conan or Thriller (nobody in real life).