Over-all, Jezebel is more random but easier to be countered (A few PA's shut her deck down, since that means no nymphs produced from towers.) Rainbow on the other hand, has set cards and does not rely on randomness; countering him is a bit harder and he doesn't rely on randomness. Due to that randomness, Jezebel -can- be harder than Rainbow, although most of the time I personally consider more of a threat.