How to choose between a diamond and carbide saw.
For cutting relatively soft materials, the carbide rocksaw is the best choice.
The tips of the carbide picks, or tusks, penetrate between the grains of the cut material and rip whole grains or pttle chunks of material out.
The carbide rock saw needs brute force or torque and limited speed
If the material is sufficiently soft compared to the carbide tipped pick, the energy transfer is more efficiently accomplished by ripping it by the carbide tusks even when a lot of energy is wasted on excessively wide cut.
If the material is so hard that point of the carbide tip cannot engage and rip the grains out, then the best way is to grind away the grains instead of plucking them out. For this grinding action, diamond based abrasive tips of a "diamond saw" are the way to go.
For harder materials, perhaps a diamond rocksaw is the way to go.
The commonly used nomenclature is not exactly correct. While the carbide really is a saw, the diamond is rather a grinder.
The "tips" of the diamond blade have no sharp tips to speak of. They are made of flat diamond filled abrasive segments, that grind away the material under attack.
the diamond rock saw needs speed and not too much pressure.