This video introduces important CADfix terminology and concept to help you understand difference between topology and geometry.
A CADfix face contains collection of edges that usually form a closed loop. A CADfix edge defines the boundary of a face. The start and end positions of an edge are defined by referring to two points. A CADfix surface defines the 3D “shape” of the interior of a face. Point, edge and surface are geometrical entities because they represent the 3D position of an entity. Whereas body and face are topological entities because they just represent a collection of other entities. Topology is only related on how model is connected and this is what repair process focuses on. The prepare stage will focus on the quality of the geometry and its compatibility to the target system.