Not enough here to be useful.
It's not really helpful. It's just not useful to anybody having a complex discussion. I mean, yeah, preschoolers are going to understand it, but there's important things you need to be discussing with preschoolers in addition to this-- People not touching them inappropriately and similar ideas, because you need to really talk about that before it might happen.
Message
Boys and girls have different bodies, and different parts of them are used in making babies somehow.