Walt Disney World (4 parks: Magic Kingdom, EPCOT, Hollywood Studios, Animal Kingdom + 2 water parks) is best for: families with young kids, classic Disney characters, immersive themed lands, longer stays (4-7 days minimum), park-hopper convenience. Universal Orlando (2 parks: Universal Studios + Islands of Adventure + Volcano Bay water park) is best for: families with teens/adults, thrill rides, Wizarding World of Harry Potter, shorter trips (2-4 days), single-park days. Cost: Disney $159-189/day/park, Universal $115-180/day/park. Disney is much larger geographically. Both have premium hotel options. Many visitors combine both in 7-10 day Orlando trip. Tickets cheaper online than at gate.