ocr: There is an huge inherent difference between CAD and GIS. Basically, in CAD wnat you have is what youve draun, and what you see is what you get. ln GIS what you have is a Gata base of the descriptions of the features of your mocel. ln adcition to the identity and ocation of each item is its relationship to other items. what you see in GIS is whatever your Cnoose, based on any attribute oF combination of.. attributes and location Information, or based on - some relationship to other items. To illustrate this point, contrast the CAD OVERPLOT concept with a GS OVERLAY.