How is the *embed* skin to be used?

The latest version of Antville has introduced a new embed skin and the "diff" action. The "diff" action is an excellent idea. I find I do not know how I did without before already. Although, IMHO I think it needs an OK button (I know there is no updating), but its expected in the skins you press a button.

I cannot see the different between the display skin and the embed skin? There is no example of its use, e.g. story.display is used in full story skin but where/how is the embed skin used. I just want to know as it may be of use to me.

Thankfully this new skin has not impacted on my existing skins which makes it even more confusing as to its purpose as its related to the story macro

BTW, the new Antville update still kicks me back to the frontpage when I try to edit the login-form skin (I thought it was going to be fixed in this update)