Last century, the outlet mall at the end of International Drive was amazing lots of discounted run out stock, ridiculously cheap!! There was the other outlet mall down near Disney World (Vineland Ave) and it wasn't quite as good, more like a normal shopping mall with some discounted stuff. One of them was Premium Outlets, then Premium Outlets took over the other one, and now they are both Premium Outlets and pretty much the same, same shops, and very similar discounts, you find some differences in the discounts, but not sure it's enough to warrant checking out both to compare prices and then going back to the cheaper one. The International Drive one is a bit bigger, and does have a few more upmarket shops, but overall, much of a muchness. Either way, they have a lot more variety than here and everything is a LOT cheaper than here, and if it is discounted it's ridiculously cheap compared to here.
Mall of Millenia is just a great big shopping mall, like Westfield Bondi Junction or Westfield Chatswood, actually I think it may be smaller than Westfield Bondi Junction. Mall of Millenia has great air conditioning (both Premium Outlets you are wandering around outdoors between shops), again normal price is a lot cheaper than here, and if you go during sales, it's going to be much cheaper.
I wasn't at all impressed with Florida Mall, thought it was quite run down (2010, maybe it's been renovated since then?)
Now for SERIOUS bargains, you cannot go past
Nordstrom Rack Millenia Crossing this is the discount outlet of Nordstrom, so millions of different brands, with ridiculous discounts, this is the stuff that has been in the sales racks at Nordstroms and then gets sent to the discount outlet. I got some Vera Wang shoes reduced from $600US for $30US, NYDJ jeans for $25US, etc, etc... Nordstrom Rack does not have every colour in every size, it is all about the leftovers, but there are so many leftovers you are bound to find something to make you happy
And it's relatively close to Mall of Millenia, so you can do up market shopping/window shopping, and do some BIG discount shopping. Nordstrom Rack is a little bit awkward to find, it's sort of off by itself, but it is worth finding!!!!