CNC milling machine is developed on the basis of general milling machine. Both of them have the same processing technology and similar structure. However, CNC milling machine is an automatic machine tool controlled by program, so its structure is quite different from that of ordinary milling machine.

CNC boring and milling machine and processing center are the same principle. They are mainly used for boring holes with larger diameter and deeper depth. CNC milling machine is generally used for milling simple surfaces, but also for milling shallow holes. The bed structure of NC boring and milling machine is larger than that of horizontal type. The bed structure of NC milling machine is generally small in vertical type. NC boring and milling machine has tool base to change tool automatically. There is no tool base for milling machine. Tool change is realized manually in the process of processing.

At present, the CNC boring and milling machine and the processing center can be basically universal, but the Boring Machine for processing parts is limited relatively little. As for programming, the boring machine usually uses every turn 
feed when drilling, while the processing center generally uses every minute feed. Because the centripetal force of the boring and milling machine is better, the sliding pillow can extend very long, it is generally used to process box parts with 
high hole accuracy and large volume, and the boring and milling machine slides. The pillow is relatively stable, and the surface precision is relatively high. A good machining center can basically be realized.