What is the main difference between classes and objects??

Answer 1

Collection of objects can be called as CLASS.

For example: if Fruit is a class then the objects of that fruit class will be apple,orange,banana,grapes nd so on..

Class describes the object or we can called class as blueprint for an object.

Answer 2

Class is a blueprint, template, pattern. It defines what will the object of that class contain (functions and attributes). You create an object based on a class. When object is created, you can execute those functions on it. The same class might serve as a blueprint for many objects.
Try to practise it and it will become more clear to you.