1.Rigidly speaking
The drilling machine is only subjected to large vertical forces, the lateral forces are small;
Milling machines require good rigidity, as the milling forces are subject to large lateral forces in addition to large vertical forces.

2.Structurally speaking
Most drilling machines only require a vertical feed;
The milling machine not only needs vertical feed, but also the vertical and horizontal feed.

The drilling machine focus on drilling holes on the work piece.In general, the rotation of the drill bit is the main movement and the axial movement of the drilling machine is the feed movement.

The whole structure of the drilling machine is relatively simple, and the machining accuracy is very low. It can perform operations such as through holes and blind holes on the workpiece. In addition, it can perform tool replacement by itself, and can perform processing procedures such as hole boring and tapping.

A milling machine uses a milling cutter to machine the flat surface of a work piece. In addition to machining plate surfaces of work pieces, grooves and gears can also be machined on milling machines. The milling machine is also capable of machining work pieces with more complex profiles.If you want to use a drill instead of a milling machine, you can first make a fixture to position the work piece and, in addition, drill a hole in the spindle of the drilling machine to fix the milling cutter.