In his book, "Save the Cat", Blake Snyder describes how to write a good movie screenplay.
One of his pieces of advice has to do with the theme of the movie (what the movie is about). He says it's helpful if the movie is the 'same thing,...only different.' The idea is if someone is considering what movie to go watch, he needs to be able to fit it into his mental map of the type of movie it is, before he'll go see it.
When working on your business idea - you can use the same type of advice. What is your business like, and yet, different from other businesses?
One of our clients at the Center for Business Development, The Physician's Agency is a great example of this rule. They provide an agent relationship for new and current doctors. Their business model is like an agent for a football player or other sports star. It is different from that business by concentrating on doctors, not athletes.
When explaining their business model, people quickly catch on to what they are doing - and if it is relevant to them. It also makes it easy to say 'what do they do?'.
How about your business: is it the 'same thing,...only different'?