Up Milling is the process of removing metal by a cutter which is rotated against the direction of travel of the workpiece is called up-milling. It is also called conventional milling.
In up-milling, the chip thickness is minimum at the beginning of the cut and maximum at the end of cut. The cutting force varies from zero to maximum.

Down Milling is the process of removing metal by a cutter which is rotated in the same direction of travel of the workpiece is called down milling. It is also called climb milling.
In down milling, the chip thickness is maximum at the beginning of the cut and minimum at the end of cut. The cutting force varies from maximum to zero.

In a shaper, reciprocating motion of the ram is obtained by crank and slotted quick return motion mechanism

In a milling machine, the rate at which the workpiece advances under the cutter is called Feed.

A planer is a machine tool used to produce plane and flat surface by a single point cutting tool. The fundamental difference between a shaper and planer is that in planer, the tool remains stationary and the workpiece reciprocates whereas in a shaper, the work remains stationary and the tool reciprocates.
In Planning machine too, more than one tool head can be used.