What are the differences in how you worked out if you want to build a nice physique for the beach with a six pack versus someone who just wants to be a powerlifter and be overweight focusing on strength only?
The words mean itself, they have different goals. Powerlifters are obviously lifters, their goal is being powerful and lift heavy weights, they gain a lot of muscle to gain the strength, building a "nice" physique is not their goal . Bodybuilders are building their body. Although they don't build the body the same way but they all want to achieve a nice physique. A nice physique may depend on their opinion. To achieve the goal, they have to train their body to gain muscles. They do lift but their ultimate goal is just to gain enough muscle for their physique.