Whenever we write code in Html , Css in any of the compiler , first the code gets rendered and then we get the output on our web browser . So a Browser Engine is nothing but a software whose aim is to render the code and so we can see the desired output , also called as layout engine or rendering engine(as it renders the code) . Initially there was only a browser engine , but when javascript came into the context , the browser engine can't take too much load as rendering javascript is bit hard . So the another engine named Javascript Engine was made whose aim is to render the server side programming languages(javascript , nodejs , python and many more) .

Some of the popular browser and java script engines used by different web browsers are :

Google Chrome/Opera uses Blink as their browser engine and v8 or chrome v8 as their javascript engine .

Safari uses webkit as their browser engine and Nitro as their javascript engine .

Firefox uses Quantum/Gecko as their browser engine and Spider Monkey as their java script engine .

Microsoft Edge uses EdgeHtml as their browser engine and Chakra as their java script engine .

Hope it helped !!