Is there a difference between boulder and massive boulder?

Just got my first one. Not sure if there is only one boulder type or two?

I don't have Massive Boulder yet but judging from the damage I take, it seems to be stronger than Boulder. I think it may lower the user's defence as well (or attack, I can't remember).

120 vs 90 power

Correct on the lowering of defense. Input, what is better for rock mob?

I think that Massive Boulder is better. I just think that better power is better even with a possible 50% decrease in defence.