NosTale is much more by-the-book Western style MMO. Building on more of the gaps they bridge with Guild Wars, players of World of WarCraft, Warhammer Online, Age of Conan etc will find most everything about questing, gathering, crafting and phat lewt all familiar and self-explanatory.
That's not to say that there aren't a few divergences, but nothing that's astonishingly genre-changing or groundbreaking - at least not in the small portion of the game that we were able to experience. One little feature that deserves mention is while in combat, the direction you move in will slightly modify your damage and defense ratios - moving forward while striking hits harder, while back-peddling will increase your chance of NosTale Gold.
Nothing major, but does serve as encouragement for players to stay mobile during a fight, rather than just stand still, repeatedly whacking away. Some skills can also only be activated as a follow-up to a prerequisite skill - a chain system in NosTale Gold (without the directional arrow combo).
After level 10 things get a little more interesting. Building on your initial class, you get the choice of a further speciality. Warriors will become either a damage dealing Gladiator or a tanking Templar; Mages can choose either the hard hitting Sorcerer or the pet conjuring Spiritmaster; Scouts will either graduate to sneaky Assassins or long range Rangers and Priests will become either Chanters, specialising in buffs and fortification, or Clerics geared to heal the wounded and bring fallen comrades back from the grave in NosTale Gold.
Again, no wild or groundbreaking additions, but it is kind of cool getting this further layer of choice after you've had some time to get a feel for your preferred style of play. Also worth noting is that there was no use of private instancing during our play-time, everything was shared open-world with separate channels that you can switch between if a particular area gets too crowded.
The biggest new feature Aion brings to the table (available at level 10) is flight. Becoming a Daeva and developing wings allows you to take the skies, not just as a mode of transportation but for interaction and combat, too.