They are, if I'm understanding correctly, referring to what may be considered the 'traditional' OOP style (Animal, which has various properties and behaviours,

They are, if I'm understanding correctly, referring to what may be considered the 'traditional' OOP style (Animal, which has various properties and behaviours, is extended by Dog, which has its own properties and behaviours, maybe overriding those of Animal) vs a style where inheritance is use primarily to define and implement interfaces (i.e., an expected set of behaviours with no implementation included in the base class). In other words, the different ways a language supporting OOP may be used rather than what the language supports in and of itself.