There are some similarities, especially in some syntax ideas. I'd say the core difference from the DX side is that Slint stylistically aligns more with CSS on some areas and allows things such as assignments, Hypen aligns more with Swift UI and separates those things from the UI completely.

Also the integration story is quite different, where Slint is more leaning into a "component integration" model, Hypen leans more into a "just a display layer" model with strict state/UI/action segregation.