Idk if it's just me, but I think that at every art/manga/manhua i've seen, their characters seem to have the same aura. y'know, some kinda tyrant/intimidating aura...
I almost always can guess whether a pict of a character is nobunaga or cao cao even it's my first time seeing. (luckily one is chinese and other is japanese so I won't mistake them for each other cuz they always drawn in different clothes)
not to mention, in Warriors Orochi (a game by KOEI) their faces are identical (well I kinda expected it anyways considering how KOEI's games art style)