You keep the source code, methods of operation or manufacturing methods private. Companies can already do this. Patents force companies to make their inventions public information (you can access the patent), in exchange for a limited exclusive right to use this technology.
For no trivial things patent legislation is a great benefit. Everyone can access the patent knowledge. For trivial iterative things patents only benefit the patentee who gets the exclusive rights.
Copyright means anything you produce that is easily to copy, you have legal control over how it’s copied and the revenue it may generate. This is for things like art work, books, news stories, code etc. Things that can be copy and pasted or printed.
Copyright is granted when you create the content. There’s no application. It ensures someone can make money from the copy they produce. Less people would write books, if Amazon could print and sell copies without paying the author.
Military tech would be private. Even with our current IP protection system. A hostile power doesn’t care about infringing IP, there’s very little consequence for do this. If you patent military technology, then that info would be public.