Perhaps we could draw it as the difference between "would pay" and "paid".
You can put a price on something, but until someone has paid it, it seems difficult to argue that the thing is "worth" your price... to anyone. But people routinely argue this, and others believe them.
But that is what the stock market is: A constant and immediate recalculation of worth.
To take another example: Facebook obviously, at the time of IPO, was not worth what it sellers hoped it would be. At some point in the future it will be worth much more than it is today, and at some other point it will be worth nothing. Today, the agreed worth/value of one FB share is $27.
You can put a price on something, but until someone has paid it, it seems difficult to argue that the thing is "worth" your price... to anyone. But people routinely argue this, and others believe them.