Chipbreaker router bits remove excess material during nesting applications, this allows for a finishing cutter to remove the remaining onion skin leaving a superb finish. They are not very different to finishing cutters except for the grooves in the cutting edge. These grooves cut off the chip being formed by the cutting edge, relieving pressure on the tool and allowing the hot chip to fly off into the dust extraction.
Compression cutters combine both and up cut and down cut spirals to force chips into the centre of the panel. The inwards pressure prevents chipping on either surface.
Two flute router bits have a smooth cutting action and a greater finish in harder materials.