And the picture format sync rates are different. This means that there are lots of conversions involved to do the comvbersion. But it is definately doable becaus there are products for it. When displaying computer graphics on TV screen you will very easily see the limitations of the TV itself and the TV broadcast standards. Anybody who has tried to display computer graphics on a television knows that they look bad.
Colors wash out, detail is lost, and the whole thing flickers.
And that's the best scenarios. Sometimes the graphics really get distorted. While everyone knows that televisions do bad things to computer graphics, few people are sure exactly what is happening. This confusion isn't surprising. NTSC and PAL encoding are quite complex, and the reasons that they distort graphics are not always obvious.