I have books from both coaches. It seems Bowerman had great success with athletes of all specialties, whereas Dellinger’s coaching was more geared towards 5k and beyond.
Bowerman coached a lot of fast 800m runners.
Which coach had more success with 1500m / the mile?
Looking at their training on paper, Bowerman would be prescribing a bit less mileage and workouts that included more variety and strides, whereas Dellinger would be higher mileage, more straightforward workouts and a long run generally each week.