NovaMan said:
A chisel shaped cutter is more efficient at severing and removing chips. It has a square working corner, that digs into the wood, then the top plate lifts it, and the sideplate severs the chip. Chisel chain comes in two different types, round filed or ground, and square filed or ground. Square ground/filed chisel chain is the fastest cutting, but is most vulnerable to damage. It also requires an expensive grinder, or special more expensive files, plus skill and experience to keep sharp. It is best used in clean wood, where the edge will not be damaged by dirt. Round ground/filed chisel chain cuts slightly slower than square ground/filed chisel, but the grinders and round files for sharpening it are much less expensive, and it is much easier to sharpen successfully. It is good for clean to very mildly dirty wood. It is still very easily damaged by dirt in the wood.
Semi chisel has a rounded working corner and is much less susceptible to damage than chisel chain. It cuts slightly slower than chisel chain, but is more durable in dirty wood. It isn't as easily damaged by dirty wood, and lasts longer when cutting in these conditions. It is filed or ground with the same round files or grinders as for round ground/filed chisel.
Chipper has a very rounded cutter. It is even more durable in dirty wood, but is not very common anymore. Also filed/ground with the same grinders as for round chisel and semi-chisel.
Pitch is the distance between 3 drive links divided by 2, or roughly the distance between the drive links. Smaller pitches are lighter, less strong, and have smaller cutters. Larger pitches have bigger cutters, weigh more and are stronger. For small engines, a smaller, lighter, less aggressive pitch is used, to match the loads imposed upon the engine by the chain, to the power output of the engine. The same is true for larger engines, they use larger pitches to more closely match the cutting capabilities of the chain to the power of the engine.
Compliment is simply the spacing of the cutters. Full compliment has one pitch between cutters, semi skip has a cutter, one pitch, cutter, two pitches, then another cutter, then a pitch then another cutter and repeats, and full skip has a cutter two pitches, then a cutter and repeats.
Gauge is simply the width of the drive links. Smaller gauges are slightly lighter, and minutely weaker than larger gauges. The difference is really minor, and doesn't really warrant too much worry, simply match the gauge of chain to the gauge of your bar.
Hopefully this clears a few things up for you.
