Do I need separate visas?

I applied for one with my original plans leaving from Newark, New Jersey to Shanghai, China. and then flying from Shanghai to GuongZhou. But my plans changed and now I am flying from Newark to Hong Kong and then spending a night at relative and then taking a bus to GuongDong the next morning.

Will I need to reapply for another one now that my plans has changed?? Do I need to apply for a separate one if I go through Hong Kong?