@whiporee is correct.
Extra Magic Hours at night were free hours for ALL Disney RESORT GUESTS ONLY to do whatever was open. (they often closed some dining and shopping locations). The only thing reduced about it ... it was for resort guests only, which at high occupancy could be a full park. Of course, not everyone participated. This event was much better when there were several a week at each park that hosted. Once they reduced it to only maybe once a week and less hours, it became more crowded.
After Hours were a paid event for EVERYONE to enjoy attractions, had minimal shops open and FREE Ice Cream, Popcorn and Bottled Drinks. Some of the events were slightly more expensive and offered some characters and theming. This is a limited capacity event although over the years the numbers have grown.
The two are completely different events. The only thing the same is they occur after the park closes to regular ticket holders.
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Extra Magic Hours in the morning were free hours for ALL Disney RESORT GUESTS ONLY, to do whatever was open. There would often be dining at places with breakfast open. The only thing reduced about it was it was for resort guests only, which at high occupancy could be a full park. Of course, not everyone participated.
Early Morning Magic is a paid event for EVERYONE to enjoy attractions in a specific area and included a breakfast buffet. This had a very limited capacity because it was limited to one area of park, and food.
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And in case no one remembers, Disney Resort Guests used to have to PAY to do "extra magic hours." They were called "E Ride Ticket Nights". Guests would pay an extra $15 to have what became free Extra Magic Hours.
Honestly, charging for limited capacity After Hours is a great idea financially for Disney. And if these holiday After Hours events are a success we may never see another Halloween or Christmas party again.
Disney depends on non-Disney hotel guests more than their own hotel guests to fill those parks, so any decision they make does factor in those guests ... they already hooked the Disney Hotel guest, they now have to keep the non-hotel guest engaged and not moving their spending up the road.