To be blunt the difference between a cane and a crop are like a fart. The cane is silent but deadly, the crop is noisy but not too painful. And again, this is just my opinion here from my own experiences. The cane is like a white hot searing pain that lasts and lasts. A crop is a stinging sort of a bite. Yes, it can be painful but in a few seconds the pain from the crop is gone more or less. When I got the ONE swat from the cane I was sore for a good 5 days. When it landed it hurt so bad it made my knees buckle and it took my breath away. Needless to say, once was enough for me, never again. The crop however is something that I highly enjoy and highly recommend. It makes a fantastic noise and gives you that amount of pain that is both pleasant and tollerable. Go and buy one, they are not expensive.
Hope this helps some.