One of the best examples of a company that found a useful difference is Airbnb. Brian Chesky and his fellow founders discovered massive inefficiencies in the renting and hospitality market. Rather than sitting idly by and working with broken systems and overpriced hotel chains, they made a platform that allows people to rent their space to others directly. In doing so, they created a much more affordable way for people to travel resulting in massive scale and growth. Now, Airbnb has a larger evaluation than Hyatt Hotel Corporation, and although many people are skeptical of large tech rounds that are fueled by hype and over evaluation, what makes Airbnb such an interesting, and in my opinion properly valued company, is that they have truly found a unique and useful difference that places them at the core of a market that they created. With that much brand recognition and growth, it will be very difficult for other players to enter the space, and it also allows Chesky and his team to develop new projects to discover more verticals and generate even more value to customers.
Ultimately, there are so many factors to consider when starting and scaling a business, but if you focus on finding a useful difference in everything you do, then you're on the right path to success.