Hey Misled
I'm going to go to the OD in Buenos Aires aswell!
Don't worry here in our country ODs are just a couple of hours long and ADs are held in another date.
The Od that was described earlier was maybe one with few people and held by Emirates alone (not with an appointed agency like Top Fly here) so when the number of candidates isn't as much they turn it into an AD automatically. But as said, this doesn't usually happen here.
See you there!