I've seen a lot of confusion about the difference between a Guarantee Status Stateroom and IGT/OGT/VGT bookings.
What is Guarantee Status?
Guarantee Status means that when you book a particular category, Disney is not able to assign you a stateroom number at the time of booking. As you get closer to your sail date, Disney will assign you a room number. You can end up in
any stateroom that is in the category you booked. However, at their discretion, Disney may upgrade you. It's not necessarily likely that you'll receive an upgrade - but it is possible.
If you try to book a stateroom and you want to be next to or near (or maybe, even - far away from) a particular stateroom, you may wish to book a the next highest category so you can confirm a particular stateroom number where you need it.
This is just like
any other
Disney Cruise Line booking. There's nothing special about; other than the fact that you won't know which particular stateroom you're in. All the normal deposit, change and cancellation policies will apply.
On some confirmations/documentation, you'll see this referred to as "GTY". That's an abbreviation for Guarantee status.
Guarantee status is similar to a room assignment. Suppose you book category 8A. You go to pick a room, and you must select "guarantee status". You would then talk about this as "category 8A, guarantee status".
What is IGT/OGT/VGT?
IGT/OGT/VGT is a special type of discount program. In return for some very strict cancellation/change policies, Disney will sell you a stateroom that is an Inside Stateroom (IGT), and Oceanview Stateroom (OGT) or a Verandah Stateroom (VGT). You can end up in ANY category on a particular ship that is within the those types of staterooms.
Categories for staterooms on the Wonder/Magic:
Inside (IGT): 10A, 10B, 10C, 11A, 11B, 11C
Oceanview (OGT): 9A, 9B, 9C, 9D
Verandah (VGT): 4A, 4B, 4E, 5A, 5B, 5C, 6A, 7A
Categories for staterooms on the Dream/Fantasy:
Inside (IGT): 10A, 11A, 11B, 11C
Oceanview (OGT): 8A, 8B, 8C, 8D, 9A, 9B, 9C, 9D
Verandah (VGT): 4A, 4B, 4C, 4D, 4E, 5A, 5B, 5C, 5D, 5E, 6A, 6B, 7A
IGT/OGT/VGT staterooms are not available on every sailing. If they're available for the sailing you're looking at, it will be the first option listed when you click on "Inside Staterooms", "Oceanview Staterooms" or "Staterooms with Verandah" on the
Disney Cruise Line booking engine.
When you book one of these rooms, you can end up in ANY of the above listed categories that falls into the class you booked (Inside, Oceanview or Verandah). In exchange for the lower price, you give up not only knowing where your stateroom will be, but also which category it will be. Further,
no changes are permitted to one of these booking. Payment is due, in full, at the time of booking. Once it's booked, THAT'S IT. No changes. No sail date changes. No passenger changes. No name changes. Nothing. It is also completely non-refundable. You will lose everything if you try to cancel one of these. Additionally, once you are assigned a stateroom, again - that's it. You have no recourse to change the room.
The only way one of these staterooms is similar to Guarantee Status is that you don't know where the room will be located.
IGT/OGT/VGT is a stateroom CATEGORY. If you book one of these, you refer to it as OGT, IGT or VGT. (Or, if you're speaking of them in general terms, people will sometimes say *GT or XGT)
There's a lot of posts on the board that confuse the two. If you're wondering when you'll get out of Guarantee Status and have a stateroom assignment, you can refer to "guarantee status", "guarantee", "gty" or "GTY" in your question or post.
If you're wondering when you'll get your stateroom assignment based on an IGT/OGT/VGT, reference it as IGT, OGT or VGT.
Hopefully that will help clear up the confusion between the two.
sitting on the verandah in a lounge chair. 
I'll keep ya posted.
