Can you tell me about those ideas not currently present within WOW? if this was the case then it may not be WoW clone, but if all it does is further develop present ideas then it's just a WoW2. What you said before implies that there's nothing new or innovative about the game aside from developing present ideas further.
Sorry, fell asleep :P
I have already stated a few.
Basically, flying combat is one major one which already differentiates it in the way it is done.
In depth character customization is a plus.
Also the abyss contains a feel that is not present within WoW but more like WAR with open world fortresses.
The whole class system is designed so that you perform a specific role rather than being able to, "Okay today I tank and tomorrow I'll DPS". Big difference.
Skillchain like combat.
And personal stores are also used again.
Giving armour the stats of another is also very nice.
Interaction with environment (rain etc.)
A party system that is actually encouraged (I mean it is an MMO)
For me though, just the immersion you get sets it apart from WoW, and that is something I enjoy.
If further developing ideas until they are innovative/shiny/strange/new does not constitute being different, then all games are based off of one single idea of being a form of entertainment (as an extreme view that is ahaha XD)
And if you wish to call Aion a WoW clone because of what you see, then that is fine. I'll just call WoW and every game henceforth an EQ clone instead.