Javascript: new vs return object

Question

Possible Duplicate:
Function vs. Object Literal Notaion - is there a diifference?

I'm playing around in nodejs and I got to a place where I can do the same thing in two different ways.

var x = function(arr) {
    this.get = function(index) {
        return arr[index];
    }
}
var myVar = new x([1,2,3,4]);

or

var y = function(arr) {
    return {
        get: function(index) {
            return arr[index];
        }
    }
}
var myVar = y([1,2,3,4]);

There's obviously some difference between these two methods, my question is which? Thanks