An Object is a class of things one thinks about first in designing a program and they are also the units of code that are eventually derived from the process. In Object-Oriented Programming (OOP), each thing is made into a generic Class and instances of the Class are referred to as an object. Classes are specific or generic in nature. Specific Classes are specifically designed to represent a specific class of things. Generic Classes are templates of how an object can be manipulated. ( See: https://searchapparchitecture.techtarget.com/definition/object).
For example, there is a thing in the system defined specifically to caption the concepts of a car (i.e., wheels, chassis, steering wheel, etc.). There may also be a Generic Class that represents a collection of things. The Generic Class can be applied to many different classes to create a collection of things (i.e., cars).
Source: Reference Architecture (RA)