The style of programming in pre-OOP languages and in OOP ones are different as well as their vocabularies. Here you are an example: there is no procedure anymore, there are class methods.
Yet another example: an object-oriented programmer may define an abstract data type by encapsulating its implementation and its interface into a class.
One or more instances of the class can then be instantiated.
An instance of a class is known as an object.
Every object has state and behaviour.
The state is determined by the current values that are stored in the instance variables.
The behaviour is determined by the instance methods of the class from which the object was instantiated.
Inherited abstract data types are derived classes or subclasses of base classes or superclasses. We extend superclasses to create subclasses.
Within the program the programmer instantiates objects and sends messages to the objects by invoking the class's methods (or member functions). Instantiate an object means create instance of a class.
An object oriented program defines abstract data types, encapsulates those abstract data types into classes, instantiates objects, and sends messages to the objects.
To make these words even more confusing, almost every item or action used in the OOP vocabulary has evolved to be described by several different terms, often depending on the author(s) who wrote the particular book your are happy to be reading. For instance, we can cause an object to change its state by sending it a message, invoking its methods, or calling its member functions.