Besides being larger and can carry heavier loads and armour, the advantage of Ka-52 is that it has 2 radars, one on the mast and the other inside the nose, capable of tracking and targeting aerial and ground targets.
Standard Z10 has no radar, though a new mast radar has been developed but we have not seen them in services yet. Rumour on China buying Ka-52 thus has some weights in it, Ka-52 can also be used as a bench mark reference for China's development of heavy attack helicopter.
The downside of buying Ka-52 is the uncertainty of delivery due to Russia's production commitment to their war in Ukraine.
The Ka-52 is kind of complicated to copy. My main concern is it will be an evolutionary dead end for China. It is really advanced at what it does. One of few helicopters with ejection seat. It is also faster than the US Apache. The electronics are kind of okay in terms of effectiveness but China if they want to can do something better in that regard. But mechanically and in terms of engine. Just too complicated to copy.