Those screenshots are from the previous Project M version, idk why we haven't updated them. The sourspot got a bit smaller and was moved up compared to this picture :
Basically the sweetspot is the bulb, the sourspot is the spore explosion.
I believe the sourspot sends at 40-45° (+- 18° because of DI) to the side (whichever side of you the opponent is at), and the sweetspot is a meteor so it sends the victim straight down. I don't think there's a third hitbox that sends directly upwards.
But, like with every other meteor in the game, if you hit a grounded opponent with the sweetspot, they will bounce vertically. That bounce takes away 30% of your move's knockback but the hitstun remains the same, so they're closer to you when the hitstun wears off and thus it is a great way to start a combo.