I think Nick was the superior fighter, a little bigger, more technical boxing, more volume and very similar grappling styles. At his peak Nick was an elite level fighter who fell short of proving it, Nate was a high level fighter who was tough and skilled enough to hang with them. Both may not be the most decorated but still some find themselves among absolute legends of the sports and both have some unforgettable historical moments in the sport.
It's pretty insane how similar their styles and careers were, been a fair few siblings in MMA and very few had comparable styles and careers. Good genetics.