A can of Coke has a picture of a bottle of Coke printed on it.
advertisers have been enjoined to "sell the sizzle, not the steak".
CocaCola has taken this advice to heart.
And they've succeeded.
They've succeeded to the point that they can no longer sell the real thing.
They can only sell a picture of it.
Without the picture, people wouldn't recognize it.
The real thing isn't the Real Thing anymore.