I'm really not particularly qualified to answer this definitively, so I forwarded your question along to an intellectual property attorney friend of mine, Paul Overhauser, of Overhauser Law Offices, LLC, and here's what he had to say:

A copyright gives you the right to stop someone else from "copying" (or using) software that you own. However, if someone else creates their own software from scratch, that would not be "copying" so there is nothing you could do about that.

However a patent protects an "idea." If someone else uses your patented idea, they are infringing, and you can get a court to make them stop, even if they just happened to come up with the same idea on their own.

Think of it this way. Microsoft can prevent someone for distributing unauthorized "copies" of Microsoft Word, but they can't prevent Corel from distributing WordPerfect. This is because Microsoft has only a copyright on Word, not a patent.

I'm not sure how to get copyright and legal protection in India, but in the U.S. you can find lots of great information at Copyright.gov and The US Patent & Trademark Office.

Unique business models can be patented. For example Amazon was recently issued a couple of controversial patents:

• 6,963,867 - Search query processing to provide category-ranked presentation of search results
• 6,963,848 - Methods and system of obtaining consumer reviews

You can find copies of these patents at USPTO.gov.

Thanks for that concise and informative answer, Paul!