The headline additions are:

- Tail calls make recursive and state-machine-style code more efficient without growing the call stack.

- Exception handling gives Wasm a standardized control-flow mechanism for exceptional conditions, rather than leaving every embedding environment to invent one.

- Multiple memories and 64-bit addressing remove practical size and layout constraints for larger or more complex modules.

- GC types enable richer language runtimes—such as managed objects, arrays, and exceptions—to be represented more directly in WebAssembly.

- Relaxed SIMD trades some determinism for potentially faster implementations on diverse hardware.

Also:

- typed references,

- profiles, and

- richer constant expressions