What's the difference between a software patent and copyright?

It's a question that many developers ask, whether they're open source fans working on re-implementing a particularly smart commercial idea, or commercial developers seeking to be directly inspired by the work that other companies have already accomplished: what's the difference between a software patent and a software copyright? You might be surprised at the answer:

    About Software Patents and Copyrights

The answer included is from a patent and intellectual property attorney, the chap who helped me get a registered trademark for my domain name many years ago, as it happens.