The difference is not merely one of a 10x productivity imbalance, it's a huge effectiveness difference on the scale of thousands or even millions of times.
Looking for "10x productivity" developers is a side-show, it's treating software like factory work. Look for developers who can work more effectively. Developers who you can rely on to deliver a product that is absolutely better along every axis than the competition. Developers who won't just pump lines of code into the repo but who will actively work to improve the quality of the code base over time and increase the total development velocity of the company. Developers who will take the time to look at the internal processes and tools that the company uses and seek to improve them when necessary. Developers that will serve as strong mentors to other developers on the team, and improve their quality as well. And too developers who will be looked up to and admired and will serve as a reason for why other developers enjoy working at the company.