Similar figures are figures of the same shape but different (or same) size. Thus, they look the same, but one is bigger than the other by a scale factor.
Congruent figures are figures of the same shape AND same size. They can be mapped onto each other using any type of transformation (besides dilations).
John technically doesn't have anymore. Instead, sally owes John 59763 bottles of water. If you're asking for something mathematical, John now has -59763 bottles of water.
