This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
I take it that you mean "real-world" instead of "real-time".
A real-world example is a "fruit". We can consider using either an interface or an abstract class. Since all fruits have a common property, weight, an abstract class should be used rather than an interface since interfaces can't contain variables. (Though, you might find a reason to use both an abstract class and interfaces).
Concrete classes of fruit could be "apple", "bannanna", and a "pear".