Peter,
I would suppose that the major difference is quality. A much higher quality is required for digital still photography because the CCDs can resolve more, the computer monitor resolves more than the standard television set, and the paper print requires maximum resolution. And the viewer spends a lot more time looking at a still photography, than a video, with motion and changing images. Any loss of quality is immediately observable in the digital camera output.
Cheers,
Tyler Monson
Seattle, Washington