ConcreteFactory is a simple factory pattern.
It differs from the static factory because it is NOT static and as you know: static => global => evil!
Therefore, you can have multiple factories, differently parametrized, you can subclass it and you can mock-up it.
You can also find these code on GitHub
ConcreteFactory.php
ConcreteFactory.php
VehicleInterface.php
VehicleInterface.php
Bicycle.php
Bicycle.php
Scooter.php
Scooter.php
Tests/SimpleFactoryTest.php
Tests/SimpleFactoryTest.php