Why are engineering design drawings and product design drawings not protected by invention patents but protected by copyright law? How to tell?

Patents protect technical solutions that are novel, creative, and practical; engineering design drawings and product design drawings are not converted into application documents for patent application protection, and they cannot obtain patent protection; patent protection It is an application for protection.

Different from this, copyright is generally protected voluntarily, that is, the work (protected drawings, literary works, photography and video works, etc.) is automatically protected by copyright from its birth, as long as it is Just prove that you are the original author.