difference between webpack 4 Hot Module Replacement and react-hot-loader

Question

Implementing Hot Module Repacement using webpack 4 example works perfectly, and my react component are rendering smoothly as well.

However in the webpack documentation at the end, there is mentioning of react-hot-loader.

Can any one explain the difference in HMR in webpack4 and HMR implemented using react-hot-loader ? Is there any difference when implementing react redux