One thing I've been told many times was that "styles make fights". This was mainly regarding MMA, but I believe the same applies in BJJ. Although at the highest levels of elite BJJ, right now the athletes are strong from essentially everywhere... differences in styles can be more apparent when people are coming up in the ranks.
One very glaring difference is the difference between a novice with wrestling experience, and one without.
When faced against each other, almost always the beginner with the wrestling will assume the top position, and the other will play guard.
Now, what is interesting is that the non-wrestler will get crushed almost every time if he attempts to use sweeps that eventually turn into wrestling take-downs because he is out-matched in that area severely. (whereas the wrestler is able to turn sweeps into wrestling take-downs at will against inferior wrestlers).
What eventually happens?
The wrestler continues to derive success from turning pretty much everything into a wrestling take-down or a scramble, whereas the non-wrestler begins to rely on more technical guard work to dominate position against anybody regardless.
Not that either approach is wrong, but just an observation I've made.
Now a very exciting match featuring Justin Rader