Patent right is regional, that is to say, in which country or region the patent right is obtained, it will be protected in which country or region. Generally speaking, China's patents have no effect in the United States, and American patents have no effect in China.
Therefore, there is no standard to judge whether an application is good or not in any country. It can only be said that you can apply for a patent in which country you want to obtain rights and protection.
Can I apply for both? What is the difference?
You can apply for both.
The specific operation method is to file a patent application or PCT international patent application in the United States within 12 months after China applies for a patent, with the United States as the designated country, and at the same time, it is required to give priority to the earlier application in China.
Patent applications in China and the United States will be examined according to their own patent examination standards and granted separately. After authorization, it is protected by the patent law of the country in the corresponding country.