EmberJS: What's the difference between get(obj, 'prop') and obj.get('prop')?

There are two ways in EmberJs to retrieve object's property.

You can either use myObject.get('propertyName'), which is more common, or you can use get(myObject, 'propertyName')

Is there any implementation difference between these two? Or is one of them just a shortcut to the other? Are there any performance benefits/costs?