With the Factory pattern, you produce instances of implementations (Apple, Banana, Cherry, etc.) of a particular interface -- say, IFruit.

With the Abstract Factory pattern, you provide a way for anyone to provide their own factory. This allows your warehouse to be either an IFruitFactory or an IJuiceFactory, without requiring your warehouse to know anything about fruits or juices.

Factory pattern: The factory produces IProduct-implementations

Abstract Factory Pattern: A factory-factory produces IFactories, which in turn produces IProducts :)

[Update according to the comments]
What I wrote earlier is not correct according to Wikipedia at least. An abstract factory is simply a factory interface. With it, you can switch your factories at runtime, to allow different factories in different contexts. Examples could be different factories for different OS'es, SQL providers, middleware-drivers etc..

The Abstract Factory Pattern

• Provide an interface for creating families of related or dependent objects without specifying their concrete classes.

• The Abstract Factory pattern is very similar to the Factory Method pattern. One difference between the two is that with the Abstract Factory pattern, a class delegates the responsibility of object instantiation to another object via composition whereas the Factory Method pattern uses inheritance and relies on a subclass to handle the desired object instantiation.

• Actually, the delegated object frequently uses factory methods to perform the instantiation!

Factory pattern

• Factory patterns are examples of creational patterns

• Creational patterns abstract the object instantiation process. They hide how objects are created and help make the overall system independent of how its objects are created and composed.

• Class creational patterns focus on the use of inheritance to decide the object to be instantiated Factory Method

• Object creational patterns focus on the delegation of the instantiation to another object Abstract Factory

Reference: Factory vs Abstract Factory

Extending John Feminella answer:

Apple, Banana, Cherry implements FruitFactory and that has a method called Create which is solely responsible of creating Apple or Banana or Cherry. You're done, with your Factory method.

Now, you want to Create a special salad out of your fruits and there comes your Abstract Factory. Abstract Factory knows how to create your special Salad out of the Apple, Banana and Cherry.

public class Apple implements Fruit, FruitFactory {
    public Fruit Create() {
        // Apple creation logic goes here
    }
}

public class Banana implements Fruit, FruitFactory {
    public Fruit Create() {
        // Banana creation logic goes here
    }
}

public class Cherry implements Fruit, FruitFactory {
    public Fruit Create() {
        // Cherry creation logic goes here
    }
}

public class SpecialSalad implements Salad, SaladFactory {
    public static Salad Create(FruitFactory[] fruits) {
        // loop through the factory and create the fruits.
        // then you're ready to cut and slice your fruits 
        // to create your special salad.
    }
}