He didn't say 'completely different' - he said it needed to be unique. Different ideas there.
He didn't 'need the money' - the idea of putting in a theme park was to make the project seem more viable and safer to commit to. The idea of a theme park (MK) wasn't built to fund WDW.. it was included in the WDW plan to make the project seem viable and desirable to outsiders. It was part of the 'bait' to get WDW the legislation they wanted, and the support for the project. Building it first was a compromise agreed to make the project viable.
Don't forget Disney had been searching for years on a place to build another Disneyland-style park. Don't misconstrued 'there will never be another Disneyland..' comment to mean he would never do another park of that style again. It means there will never be one to replace what Disneyland was.. the first of its kind, the beloved, etc.
It's like loving your child and saying 'There will never be another like raven24...' - it doesn't mean you won't have another child.. it means no other child can replace in your heart what raven24 was to you.