what is the difference between object and instance?

Answer 1

They are synonymous.

Answer 2

an object is a class instance

Answer 3

They are the same thing. When an instance of a class is initiated, then the object of the class has been created, or initiated as well. Because an object is just an instance of a class that has been created or initiated. There can be multiple objects or instances of any given class. The class is the blueprint for what the object or "class instance" will be.