When choosing a Unique Selling Point or Brand Position it is easy to think "What makes my product or service different?" and then take that as your position.
Better though is a marketing-led approach. Identify a position that is unique and do two things:
1. say you have the best gizmo in that domain.
2. focus relentlessly on making your gizmo the best by doing it more than anyone else.
If you have chosen a unique position then, assuming a reasonable level of compentence, you will quickly have the best gizmo in that domain. i.e. become expert by only doing one thing again and again. Then you become the best and you have a virtuous circle...
See the excellent Volvo point below (from a very good article).
All cars will promise to get you from A to B. There is no differentiation in that claim. However, if Volvo’s promise is the get you from A to B with maximum safety, its car has established a category and an identify in that category. Volvo has positioned itself as a safe car. But what if another car manufacturer positions its new car as a safe car? Volvo and its new competitor will need to move to the next step, that of differentiation. If the competitor sets a much lower price on its car, it has established a differentiator. The competitor is offering a less expensive safe car. But it must think twice about doing this. Will a buyer who wants a safe car believe that the lower price safe car is as safe as the more expensive safe car?