I've played Native almost on a daily basis for over two years ( since early beta ), all game modes, mostly battle, clan matches and duelling, and I've played most of the MP mods coming out for WB from the beginning, including cRPG, but I think a skill comparison is difficult for a number of reasons.
Different players play different game modes across the modules, in Native you will more or less only find a high skill level on Nditions and IG Battlegrounds - ZHG and 22nd Siege and TDM are more or less only visited by nåbs, whereas in cRPG you can actually find a few decent players playing Siege mode ( though battle and duels are still where you find more accomplished players ). All clan people in Native ( EU ) play on IG Battlegrounds these days however and the skill level there is quite high in the evenings. I dare also say that the current Native clan and duel tournaments, at least in the EU where there's competitive leagues like the ENL, is more e-sporty than the otherwise excellent and dynamic Strategus of cRPG. Duels are also very different, taking place without armor, shields and without any kind of build or equipment crutches whatsoever. And yes, the speed is faster in Native, plus there's other 'gimmicks' ( game-breakers to some ) like superfast feinting with 1handers, lolstabbing with 2handers and superduper accurate and speedy throwing and ranged, plus a lot of other things that have been fixed in cRPG.
The amount of players being fair manual blockers on battle servers is of course higher in cRPG ( at least you notice it more ), where not using a shield is more viable than ranged-heavy Native, and cRPG battles can at times feel a bit like a mix of duel and battle mode.
Inexperienced or bad players can do much better in cRPG than in Native, though, as they can hide a lot of their shortcomings behind levels and armaments. These players will usually just go archers or xbow in Native but will only do reasonably well in groups.
I also find that much of the playerbase in Native, if you go the right places, have played the game longer than much of the playerbase in cRPG, which is only natural given that cRPG is a mod that was developed a good deal of time after WB was released, though of course a whole lot of veteran Native players have gone over to cRPG ( but never the other way ) or play both. It is my impression that many new Natives come directly from SP and many new cRPGers come directly from MMOs, *very* roughly speaking. The chat language is very different in cRPG, with lots and lots of cursing and leet speek which you almost never find on Native servers. I guess this is where the Native prejudice that cRPG has a younger community stems from.
This is not cRPG bashing btw, I definitely prefer this module over Native.
My impression is based off the EU communities only, I know the NA communities are smaller and less organized ( no offense intended whatsoever if there's any delicate toes out there, WB is just mainly EU including the enormous Russian and Turkish communities ) but I have little first-hand experience with them, except from forum activity, a few clan matches, some random pubbing and the Nations Cup a year back.
All in all the two tribes are much alike, but game mechanics imposes some differences.