Dancing Zombie enters the screen slower, but does not walk as far inwards before summoning. This makes him harder to target if you forget Cherry bomb or something.
Cob Cannon’s projectile is SUPER slow for some reason.

Catapult Zombie has less basketballs and will charge you way sooner, so his high HP turns him into a bulldozer (umbrella leaf is no longer a completely nullifying counter. It just delays when the damage happens as you must build enough DPS to take it out quickly)

I also believe the limitations of the hardware made the Jack in the Box zombie have a shorter fuse. This makes them way more likely to blow up before dying and doing no damage.