What Is BIM?
BIM is a process not an application. It’s based around models used for the planning, design, construction and management of building and infrastructure projects faster, more economically and with less environmental impact. These BIM models are different from CAD drawings that may be 2D or even 3D. BIM models are made up of intelligent objects that when changed stay updated throughout the design no matter who is working with it.

What Is Revit?
Revit is a single application built for Building Information Modeling with features for architectural design, MEP (mechanical, electrical and plumbing) and structural engineering and construction. Revit is not BIM. Revit is built for BIM. Revit and other applications made for BIM help designers design, simulate, visualize and collaborate in order to capitalize on the advantages of the interconnected data within a BIM model.