MEAN vs LAMP

JavaScript vs PHP

Choosing Node.js locks all code on your web server into JavaScript.

PHP is a server-side scripting language designed primarily for web development but also used as a general-purpose programming language.

PHP code may be embedded into HTML markup, or it can be used in combination with various web template systems, web content management systems and web frameworks. PHP code is usually processed by a PHP interpreter implemented as a module in the web server or as a Common Gateway Interface (CGI) executable. The web server software combines the results of the interpreted and executed PHP code, which may be any type of data, including images, with the generated web page.

PHP code may also be executed with a command-line interface (CLI).

Express vs Apache

Express is a node.js application. A node.js web application is a full-fledged web server just like Apache.

If you're prepared to re-write your PHP in JavaScript, then yes, node.js can replace your Apache.

Node.js may be faster than Apache, as Node.js is entirely non-blocking and event-based, allowing for true concurrency among requests. But you may have problems finding modules/libraries which substitute some of Apache functionality.

some projects use node.js as the front-end load balancer for other servers (including Apache).