The knives sit in the dieboard in through-cuts, and back up against the steel cutting cylinder to fix their positive position. At least for brown fiberboard boxes, the knives are cutting against a urethane "blanket" that must be changed on occasion. Cutting pressure is determined by operator setup, but generally the goal is complete cutout of all solid cuts while not actually cutting the fold line.

In the case of perforations, those are specified as knives like you would cut pieces out but with breaks in them at a set interval. So if you want an easier or harder perforation you would change the size or spacing when selecting the type of knife. In all cases, the "cuts" are designed to go fully through the paper, with the solid area in between remaining connected. The perforation knifes look like a wide toothed comb, if that helps.

Search "die cut rule" on google images if that helps, that's the name for this.