In short, they are very different libraries for very different purposes, but yes there are some vague similarities.
Redux is a tool for managing state throughout the application. It is usually used as an architecture for UIs. Think of it as an alternative to (half of) Angular.
RxJS is a reactive programming library. It is usually used as a tool to accomplish asynchronous tasks in JavaScript. Think of it as an alternative to Promises.
Reactive programming is a paradigm (way of working and thinking) where data changes are observed from a distance. Data is not changed from a distance.
Here is an example of changed from a distance:
// In the controller.js file
model.set('name', 'George');
The Model is changed from the Controller.
Here is an example of observed from a distance:
// logger.js
store.subscribe(function (data) {
console.log(data);
});
In the Logger, we observe the data changes that happen in Store (from a distance), and write to the console.
Redux uses the Reactive paradigm just a little bit: the Store is reactive. You do not set its content from a distance. That’s why there is no store.set() in Redux. The Store observes actions from a distance, and changes itself. And the Store allows others to observe its data from a distance.
RxJS also uses the Reactive paradigm, but instead of being an architecture, it gives you basic building blocks, Observables, to accomplish this “observing from a distance” pattern.
To conclude, very different things for different purposes, but share some ideas.