Apple Logic Pro /LogicExpress Discussion

Hey,

     This is one of those things I should probably know, but I'll ask it anyway.  Eat humble 
pie, wash it down with a swallow of pride flavored latte.

      I hear both VST and Audio Unit being thrown around with regards to Logic.   What is 
the difference?

      I am about to download a demo (DUY) and it wants to know if I want VST or AU.

      pete_buchwald@yahoo.com

     Thanks,

             Pete