I am trying to understand internal working of javascript and node.js v8 engines, I understand both use single thread event loop. And javascript engine uses execution context loaded into call stack.
This figure is my reference to understand internal working of JS

And node.js maintains thread pool etc, so internal working of node.js and JS is different? Is my understanding correct , can someone briefly explain?
Someone will definitely explain this better, but "JS" is a programming language,that can be run on various interpreters (or engines), while "node.js" is an execution environment designed to run "JS" programs on a server environment, using "V8" as its interpreter.
Here's a list of JS engines: https://en.wikipedia.org/wiki/List_of_ECMAScript_engines
What is node JS: https://en.wikipedia.org/wiki/Node.js