How is Spring Cloud Gateway different from Zuul?

I have been using Zuul as the edge service and API Gateway. Recently I have noticed that Spring Cloud Platform release Spring Cloud Gateway. What is the difference between the two gateways? Why is the Zuul not extended to support the functionalities in S-C-Gateway? What was the driving factor for a new library altogether? When should it be used?

I am the author of spring cloud gateway. Zuul is built on servlet 2.5 (works with 3.x), using blocking APIs. It doesn't support any long lived connections, like websockets.

Gateway is built on Spring Framework 5, Project Reactor and Spring Boot 2 using non-blocking APIs. Websockets are supported and it's a much better developer experience since it's tightly integrated with Spring.