Scale seems to be the core differentiator.
When you break down the engagement elements of a theme park (the animatronics, sensor-driven interactions, VR immersive environments, the drama, the anticipation etc);
they are not particularly spectacular in and of themselves. Some motors, hydraulics, sensors, touchscreens, motion cameras, funky music, colours, fireworks…
It is when they are manifested on a BIG scale, in tandem; when they literally envelope participants; and are wrapped up in a unified, scripted experience; that some magical transformation happens.
A multitouch screen is fun – drag your finger across the digital pond, make ripples, scare the fish… A multitouch multisensory fully immersive environment capable of accommodating large groups of people – now that scale bumps the experience exponentially beyond the actual component technologies. See http://www.blooloop.com/PressReleases/d-strict-to-unveil-Live-Park-the-first-user-gen/2903
The same effect can be seen in painting. Initial small studies can be exquisite, but it is the final piece, execute BIG, that is truly awe inspiring.