Cycle uses a virtual DOM as well. The difference is that React will call your component functions every time it needs to render, while Cycle will (mostly) only call them once, when the app starts up. A Cycle app is a data flow graph set up by your component functions, with a "driver" at the root observing that data flow and causing side effects, like rendering your virtual DOM or making HTTP requests.

In short: instead of a component being called with props and state and returning VDOM, in Cycle it "maps" a stream of state into a stream of VDOM.