What is the advantage of using Prototype in Javascript?

Question

I read crockford's page on private members http://javascript.crockford.com/private.html in Javascript and got a question which maybe somewhat related. Why should a developer use Prototype?

For example,

For example, I can do this

var Foo = new Object();
Foo.bar = function() { alert('Its a bar'); };
var x = Foo;
x.bar();

instead of

var Foo = function(){};
Foo.prototype.bar = function(){alert('Its a bar');};
var x = new Foo();
x.bar();

Both of these implementations do the same thing. How is one different from the other? Does this affect inheritance in any way?