Re. the above. Copying 'but not quite' may be a big problem because it cuts both ways.
Engineering/design patents for example are notoriously difficult to enforce for precisely this reason - it's usually possible to get the same function from a not quite identical design.
There's lots of reasons to argue that they shouldn't be granted since they amount to discovery of natural stuff rather than inventions, but patents for something like a chemical reaction/process/drug or even a gene are almost water tight because there is only one way for them to work in nature.
Copyright I'm less familiar with. It doesn't require making an application for it, and is most enforceable in the case of stuff of very high complexity made up of easily identified elements like written works. i.e. copying is easily proven because the chances of something identical arising otherwise are negligible.
You can register a design, but this tends to apply mostly to elements of styling or an overall 'look', enforcement is a rather more judgement based call. Certain designs (e.g. a logo) may be very unique, most much less so.
As Aidan says none of these amount to anything much unless you have the clout/money to defend them, and have a case you can reliably win which means getting over the hurdle of the defence not showing your stuff was not already in the public domain, and then that yours has been copied - and the corporates will frequently try it on. Many Eastern businesses seemingly don't care because patent law doesn't apply/isn't enforceable in their countries.
PS - a quickie added later. This is not to say that it's commonplace, or that whatever form of protection of intellectual property doesn't provide a measure of protection by putting off the less serious threats - but another issue it seems is that greed on the part of agents, and increasingly less expert/thorough examination of the (increasingly weasel worded) claims in patent applications by patent offices means that patents are now frequently granted for stuff that in truth is not novel.
So that having spent gazillions on patent cover this of itself provides no absolute guarantee that if it goes to court that you can't be blown out of the water on lack of novelty.
Another not infrequent source of weakness/method of attacking patents is to show that there was (usually accidental) prior disclosure by the inventor (e.g. sampling of prototypes, or limited selling without the protection of a non-disclosure etc agreement) that a court will deem as having placed the invention in the public domain...
