These are two different animals. Acid is a loop mixer (music creator) and Vegas is a multi-track editor. What types of things do you want to do? That will better help us answer your question.
SO I COULD USE ACID TO MIX DOWN ALL THE MUSIC (BACKROUND INSTRUMENTS) AND MAYBE EXPORT THAT INTO VEGAS..IS THERE A FORMAT FILE THAT COULD LOAD UP ACID FILES ONTO VEGAS?..BECAUSE THEY BASSICALLY HAVE THE SAME INTERFACE...SO THAT MEANS I CAN USE VEGAS TO DO ALL MY VOCALS WITH MULTITRACKING RITE?