What is a national defense patent? What's the difference with ordinary patents?

The whole process of national defense patent application is confidential, and it must be declared by an institution with the qualification of national defense patent application, and after the patent application is successful, it is also confidential and completely closed to the public. It is relatively easy to apply for a common patent, and any agency with agency qualification can declare it. After the patent authorization is successful, all patent information except confidential patents will be made public.