Actually that says China taxes residents on worldwide income, and non-residents on China-sourced income. The US taxes non-resident citizens on worldwide income.
China has a significantly broader definition of residence than does the U.S. A Chinese resident company includes companies incorporated in China as well as companies managed from China; Chinese citizens are taxed on their worldwide income for several years after they leave China, possibly indefinitely if they maintain their household, familial, or economic connections to China. In practice, this means that China effectively imposes worldwide taxation on its companies and citizens.
In the U.S. residence is a very straightforward. A company is a resident if it is incorporated in the U.S. An individual is a resident if he is a citizen, a greencard holder, or passes a mathematical "substantial presence" test.
Non-resident U.S. citizens are subject to worldwide taxation...but they have a very generous $100k floor, plus foreign tax credits for foreign taxes paid on their income.
China will tax world-wide income for non-citizens if they spend 5 contiguous years in China. I recently had my month out (ok, it was more than a year ago) to avoid this situation.
The $100k floor only applies to work done outside of the US. If you work for an American company, you'll invariably go on business trips back home, which mess up your taxes substantially as this isn't covered on the US/China tax treaty.
