Is there a benefit to separating properties between the constructed function and its prototype object?

I'm trying to gain a better understanding of oo coding in JS.

So I understand the core concept that var a = new fun(); will instantiate an object from the function, with the function's prototype object linked to all the instances. But is there a value to actually use the prototype object if I'm not linking it to anther prototype object. Say for this piece of canvas code... would it better to do this; a straight-forward constructor.

function thing(x,y,width,height,color){
    this.x = x;
    this.y = y;
    this.width = width;
    this.height = height;
    this.color = color;
    this.speed = 2;
    this.draw = function(){
        c.fillStyle = this.color;
        c.fillRect(this.x,this.y,this.width,this.height);
    }
    this.update = function(){
        this.x += this.speed;
    }
}

var instance = new thing(100,100,100,100,'red');

or would it better/faster/more readable to keep all the shared functions/properties in the prototype object...

function thing(x,y,width,height,color){
    this.x = x;
    this.y = y;
    this.width = width;
    this.height = height;
    this.color = color;
 }

 thing.prototype = {
    this.speed = 2;
    update: function(){
        this.x += this.speed;
    },
    draw: function(){
        c.fillStyle = this.color;
        c.fillRect(this.x,this.y,this.width,this.height);
   }
}

var instance = new thing(100,100,100,100,'red');