I think it's worth mentioning that with a patent, nobody else is allowed to use the patented idea. This holds even if they have never heard of you before, and were entirely unaware your patent (or your version of the patented concept) existed. You are granted a monopoly.

With a copyright, people are allowed to do anything similar to you, so long as they do not derive their work from yours. Someone unaware of your work cannot infringe your copyright. You do not have a monopoly on anything, you are just protected against someone deriving their work from yours directly.

This difference probably factors into how easy it is to win a lawsuit: for a copyright infringement, you need to show they made a copy. You wouldn't be bringing suit in the first place if there were substantial doubt in that area. It also factors into how easy it should be to get a patent vs a copyright: a patent closes off much, much, MUCH more idea-space than a copyright.