Ok, Ralph Brennan’s are real beignets. While comparing them to Cafe Du Monde is setting yourself up for disappointment, they are in the same ballpark and usually very good.
The Mickey “beignets” in the park are a delightful treat, but they’re not really beignets. That’s like comparing authentic Mexican food to Taco Bell. You get a Mickey beignet because you want a Mickey beignet, not because you want a beignet-beignet.
You’ll need to eat both on your trip, obviously…