I'd be curious too, as I have only seen the active and retired discount of a package (as announced, now that I think around 2014) hotel and tickets, 3 to 5 days, and I didn't think the savings was that much. Plus, I don't need a ticket.
Active Duty and Retired also can get discounted tickets from the ITT offices. I don't think you can buy them directly through Universal.
I can't find where the hotels say what MIL means, but I think I remember seeing only Active Duty.
Thank you to all the military. I am glad Universal offers savings to all military.