The reason guys are 400/800 or 800/1500 depends a lot on their muscle fiber makeup and background growing up. Guys like Symmonds could never go faster than 47 in an open 400 and guys like Rudisha would struggle at 1500m.
Ignoring physiological differences, how does the training differ between a speed based and an enduranced based 800 guy? The 400/800 guy would likely do less mileage, but even this isn't always true considering Murphy does roughly 50-60mpw, Symmonds does 50-60mpw, yet Solomon does close to 80 miles a week in the off season. So it seems mileage is not the main factor or differences in these types of athletes.
Does anyone have any insight on some specific things that 400/800 guys focus on more compared to 800/1500 guys? Just looking for a discussion about training