Tokyo Disney Resort includes Tokyo Disneyland, modelled after the one in California, and also Tokyo DisneySea, an original theme park with seven 'ports' evoking locales real and imagined (the Mediterranean and 'Mermaid Lagoon', for example). DisneySea targets a more grown-up crowd, but still has many attractions for kids. Both resorts get extremely crowded, especially on weekends and during summer holidays; you'll have to be strategic with your FastPasses. Book admission tickets online to save time.
There are 'designated picnic areas' outside the main entrance for packed food. You can re-enter the park with a hand stamp. A huge mall, Ikspiari, with cheaper fast food options, is also just outside Maihama Station, before you enter the resort.