What are differences between Ext.create() and Ext.define() in SenCha Touch

Question

I have been learning SenCha Touch for awhile and still feel confused when trying to create a store.

In the SenCha Documentation, it says to use Ext.create() Example

Answer 1

Ext.create - to create an instance of a pre-defined class. - the class was defined using Ext.define - used to define the data and behavior of a component. which will be used later.

Ext.define - to define your own class definition - reusable component. - instances can be created using Ext.create API.

Answer 2

define is for declaring a class.

Ext.define('Foo', {
    extend: 'Bar'
});

// Similar to:
public class Foo : Bar {
}

create is for creating an instance:

var o = Ext.create('Foo'); // Can also have var o = new Foo();

// Similar to:
Foo o = new Foo();