In ECS you are decoupling data from behavior, which is basically the entire paradigm of languages like rust and go. You could argue that by defining systems in a way that they run on certain components you are defining behavior and data in one, but I think that's a stretch.
It clearly differs from OOP when I have 2 entities with components that have overlapping and non-overlapping systems. If e1 has components c1 and c2, and e2 has components c2 and c3, and c1 and c2 are used in system s1 while c2 and c3 are used in system s2, I don't see how you would model that with OOP without adding data to classes that don't need it. In OOP both e1 and e2 would need all the logic from s1 and s2, or needlessly specialized versions of s1 and s2. Which would be solved via inheritance (either class based or interface based).
In ECS your data exists in an array of components and any part of your program can operate on any component however it wants. I've never needed message passing for anything I've worked on.
That's not to mention that the main benefits of ECS have nothing to do with language paradigm. ECS main advantage is cache coherency and easier parallelism.