websocket php vs node js

Websockets are a transport built on TCP sockets. If you'll notice in the link you provided, the author recommends decoding data frames manually. There are projects that will help you with this, as @oberstet recommended (see also https://github.com/nicokaiser/php-websocket). @Kanaka has a great explanation for the difference between websockets and raw TCP sockets here.

Using node.js is certainly a smart, low-overhead way of rolling out a server for websocket connections. Another option is to use a realtime network. PubNub in particular has a blog post on how to write a chat app in 10 lines of code which is pretty accessible. Briefly, the code is:

Enter Chat and press enter
<div><input id=input placeholder=you-chat-here /></div>

Chat Output
<div id=box></div>

<script src=http://cdn.pubnub.com/pubnub.min.js></script>
<script>(function(){
    var box = PUBNUB.$('box'), input = PUBNUB.$('input'), channel = 'chat';
        PUBNUB.subscribe({
            channel : channel,
            callback : function(text) { box.innerHTML = (''+text).replace( /[<>]/g, '' ) + '<br>' + box.innerHTML }
        });
        PUBNUB.bind( 'keyup', input, function(e) {
            (e.keyCode || e.charCode) === 13 && PUBNUB.publish({
            channel : channel, message : input.value, x : (input.value='')
        })
    } )
})()</script>

A simple approach like this will allow you to cut out the server hosting and configuration entirely. Hope this helps!

This is like asking "what's the difference between PHP and HTTP". Node.js is a technology framework you write code in. WebSockets is a protocol which can be implemented using a technology framework. You can use Node.js to implement the server-side aspect of WebSockets.