Not the author, but I can elaborate on the difference with Meteor since I have experience with both.
Meteor is not server generated but rather a SPA framework with a server side part to it. It helps you build a SPA app quickly and it also uses websockets for all the transport but usually you just send json data there.
I don't really like Meteor because the performance is not that awesome and there is problems with node since it is single threaded. Meteor still doesn't support worker threads or other similar solutions in node so if you have something blocking on the server side the entire app will go down.
Liveview in the other hand is server side only (except for the liveview part). All the state is on the server and when the state changes it will push out the changes in the template and rerender automatically. In Meteor the recommended stuff to use is pub/sub and meteor methods but you still have to rerender yourself just like in a normal SPA.
Meteor is thus simply a way to quickly build SPAs and Phoenix and Liveview is a way to quickly build SPA-like feeling to apps but with everything living on the server.
You can think of Liveview as Google Stadia but for websites. Everything is rendered on the server and you just get the updates.
