Yes, this comparison is extremely weird. The author did not really do his homework. It's like saying libpng is a replacement for Photoshop.
To clarify: Autocad is a CAD suite used for 2D and 3D drawing production. In addition to that, it is used as an implementation platform for a large number of third party domain specific software for engineering disciplines that need more intelligence on top of the basic Autocad - HVAC planning, civil construction and so on.
OpenCascade is a geometry modeling kernel - a c++ library with no "end user" gui functionality or database. Yes, such a thing is a critical part in a software like Autocad, but only one small part.
To clarify: Autocad is a CAD suite used for 2D and 3D drawing production. In addition to that, it is used as an implementation platform for a large number of third party domain specific software for engineering disciplines that need more intelligence on top of the basic Autocad - HVAC planning, civil construction and so on.
OpenCascade is a geometry modeling kernel - a c++ library with no "end user" gui functionality or database. Yes, such a thing is a critical part in a software like Autocad, but only one small part.