In fact, it is always much easier to acquire new knowledge on real examples, and luckily this is the case! Not only explained he step-by-step the difference between the methods but also provided us with a ready-to-use project for Dynamics AX 2009, which can help a lot to them who have just started working with the system.
So, I highly recommend his blog to every AX developer.
To whom it may be useful, I adapted this xpo-project to Dynamics AX 4.0.
Didn't get it right? Just reread() it and refresh() your knowledge!