I think before we try to answer the difference in training, we have to answer are bodybuilders really bigger than powerlifters?
From the study (which I can’t find), there wasn’t much difference. And looking at natural powerlifters and bodybuilders, I don’t see much difference either. The big difference in strength people see is largely because of the technique, reptittion specificty and tendon attachments. If you take deadlifts, you will not see a big difference in strength since there is not much a technique component compared to squats and bench.
Most people think powerlifters ONLY train 1-3 reps.
Nope. Most of the powerlifting routines have high reps and moderate reps done for their main and assistance exercises. Look at west side. If you take Ed Coan, he starts with 12 reps and gradually hit 1-3 reps in many weeks.
Most people think powerlifting routines do not have much volume
Nope. In fact, any powerlifter will say that volume is the key. Almost all powerlifting routines hit a body part or lift atleast twice a week. Take westside, Korte’s, Smolov and so forth. Look at olympic lifters; they are hitting the same lifts 1-3 times a day for 4-6 times a week. Their volume is much higher than most bodybuilders routine who hit a muscle once a week.
Both powerlifting and bodybuilding overlaps a lot in their training.