Objects: data types such as sound, graphics, text, and numeric values that you create in Flash and use to control your movie. (OBJECTS ARE LIKE NOUNS)
Ex. a Date object will get the time and date for you.
Classes: Collective groups of objects.
Ex. built-in classes in Flash: Sound class, Video class, Math class, MovieClip class, etc.
Objects
The most common object in Flash is the Movie Clip, which has properties that can be controlled, there are also date, color, sound, and math objects as well as others.
You can also have "Homemade Objects", which are your own creation. These are more difficult to understand because you cannot see this type of object on the stage. This type of object can also have properties, but there is no physical evidence of these properties, they live in your mind instead. These are useful for storing and applying information about something you create and came from the need for programmers to make their own objects with their own instructions.
example:
Task for boiling a kettle:
Fill (kettle);
TurnOn (Kettle);
CheckBoiled (kettle);
These methods can all be combined in one Kettle Object, grouping what needs
to be done into an object which can be called in programming.
***note: Before you use objects, you need to be
able to identify them, so you give them names.
***note: Instances and objects are synonymous
More on Classes:
With Actionscript 2.0 you can make your own custom classes.
ActionScript 2.0 is an object-oriented language. Like ActionScript, OOP languages are based on the concept of classes and instances. A class defines all of the properties that distinguish a series of objects. For example, a User class represents a bunch of users who are using your application. Then, you have an instantiation of the class, which, for the User class, is one of the individual users--one of its members. The instantiation produces an instance of the User class, and that instance has all of the properties of the User class.
Flash includes built-in classes that provide everything from basic, or "primitive," data types (Array, Boolean, Date, and so on), to custom errors and events, as well as several ways to load external content (XML, images, raw binary data, and more). You can also write your own custom classes and integrate them into your Flash documents or even extend the top-level classes and add your own functionality or modify existing functionality. For example, you can make a custom Person class that contains custom properties for the person's name and age. You can then treat this custom class as a new data type in your documents and create a new instance of the class using the new operator.
to read about creating custom classes: