If I read this correctly the gist is that it does not matter if you use heavy weights with few reps (common body builder wisdom) or lighter weights with more reps. As long as you always exercise to complete muscle fatigue you'll get the maximum for your genetics (which itself varies a lot).
Stereotyping, weightlifters who go for max numbers do 1 set of a million pounds and rest three hours between exercises, while bodybuilders do thirty exercises a day for 8 series of 15 reps each.