I'm confused but that is normal. How do we define what is a roter tiller, a tiller, and a disc.
To me a roter tiller has tines with a 90 degree hook on the end and are attached to a central shaft that rotates.
A tiller has large round disc's all set on one shaft that is set to be pulled at an angle and turn over the soil much the same as a multi bottom plough.
A disc has round disc's mounted on several shaft's and configured in a V with one or more V's comprizing the disc. It may be possible to vary the angle of the V .
A cultivator has shanks with shovels at the bottom which dig into the ground. There are two or more rows of alternated shank's and they are at 90 degrees to the tractor
Haven't a clue to what a disc harrow is.
Egon