The final scanned files include steps to clean up the scan, optimize the mesh quality, and ensure that the scanned mesh is solid. At this point we can generate the initial file based on the processed scan data. 3D design is a bit more complicated.
This involves retrieving from the mesh, creating 3D designs and their features, and fitting them to match the scanned data. Once the scanned data is recreated as a 3D design, we can generate the initial file based on the final geometry of the design file.
The main difference between these two approaches is that a 3D design file can preserve the actual geometric features of the scanned part. This means that a cylinder remains a true cylinder. The same applies to flat surfaces, cones and spheres.
It allows you to create and use coordinate planes and axes as well as part surfaces. Since the design must fit the part, any sharp edges on the original part are also preserved.
In summary, if you are looking to preserve geometric features or use the file for two-axis machining on prismatic parts, converting the scan data to a 3D file is the best option.