differences:
Cao Cao = good politian + good warlord + surperm leader
Zhuge Liang = surperm politian + superme warload + bad leader
account in history:
Cao Cao: single handed built an empire (though never an emporer

). his skills are reconizes by people of China in all ages though out all time. He went though a pharse just like Lui Bei in the begging of his carrer. (holding a small province against Dong Zhoug).
He luckier consider than Lui Bei ( because he found a lot of warlords, I mean, a bunch full of them!)
Zhuge Liang = single handed directed an empire. His carrer highlights:
alieance with Wu's Sun Quan. Taking the souther Jin provience, and the sucess in "red-clif" naval battle, the three kingdom stragies, defending the Shu empire after Lui Bei's death and Norther Campain against Wei (defended by Sima Yi).
peraonal note: I think they are actually very similar in lots of aspects, they are no official records of direct campain between Liang and Cao. It would be interesting to see how they actually interect in the battle.
and please forgive my spellings (they are terriable!!! really bad)
hope that answers your question!