The U.S. and China are racing to define the future of technology, with very different ideas about how fast it should arrive and how tightly it should be controlled. The urgency is no longer abstract. In recent weeks, China approved the world’s first commercial brain-computer interface medical device and unveiled a five-ton class electric vertical takeoff and landing aircraft that has already completed a public flight. At the same time, U.S. agencies are scrambling to speed up approvals in are...