I think the main advantage of AWA - a.k.a as Individual employment contract is to allow more flexible condition and more negotiation between employer and employees, the disadvantage might be you never able to find out that you're getting paid more than others or less because it is a privacy issue that is stated in the contract. And enterprise agreement's advantage that is fair to every employee so there won't be any discrimnation.
I hope i can help but i don't have my notes with me right now so it may not be 100% right
