Plain English Meaning
Two different kinds of flight maps. VFR charts are used when the pilot can see outside and navigate by looking at the ground. IFR charts are used when the pilot is flying by instruments alone, often in cloud, and must follow published routes and altitudes.
Full Definition
Aeronautical charts published for the two main categories of flight: Visual Flight Rules (VFR) charts, which depict terrain, landmarks, airspace, and airports for pilots navigating by visual reference to the ground; and Instrument Flight Rules (IFR) charts, which depict , , , altitudes, and for pilots navigating solely by instruments.