...
In TurboCAD, "surface" refers to a 3D ACIS object, whereas a TurboCAD surface (when TC Surface is checked in the 3D page of an object's Properties) refers to an object created with TurboCAD's internal engine, which is not an ACIS object. (See 3D Properties)
These are conversion operations that create surfaces or solids from existing objects, including surfaces, faces, and profiles. You can display the Solid/Surface toolbar by right-clicking in any toolbar area and selecting Solid/Surface. 
