When quantum systems are entangled, they have a "grade of entanglement" which can be quantified e.g. as the entropy of entanglement. There also are states of "maximum entanglement", e.g. the Bell states.
But what does it mean practically if quantum systems are less than maximum entangled, e.g. with half of the maximum entropy? Does it mean that there is a probability of 50% that the systems are (maximum) entangled? Or that they will decide in the moment of measurement with a 50:50 chance to behave like maximum entangled or non-entangled? Or does it mean something else?
Or in other words: If an observable is measured for two pairs of identical particles under the same conditions, except that the first pair is maximum entangled and the second pair less the maximum entangled, what will be the difference in the measurement results?
(A similar question was already asked in a comment here by Passiday on May 24 '13 6:18, but not really answered.)
[Edit: bolded the second, better version of the question.]