The 99's ZPT-98 gun is very much superior to the 2A46M-derived gun on the 96s. It has a high chamber pressure, is more sturdy and is L/50 instead of L/48 like on the 96. This gives it a flatter trajectory, higher muzzle velocity and avoids the flutter of the 2A46M family that significantly impacts accuracy at ranges greater than 2km. By most accounts, the ZPT-98 is based on the 120mm BWK120 gun on the PTZ-89 tank destroyer that emulated Western gun designs from the likes of Rheinmetall.
The combat weight of a ZTZ-96A is 42 tonnes. The VT-4 is ten tonnes heavier and much newer. I find it hard to believe that a design ten tonnes heavier and ten years newer will have inferior armour.
The 99A has a 1500hp engine while the VT-4 has a 1200hp engine. Whether or not the optional 1500hp upgrade is the 99A's engine is unclear.
There are contradicting sources about the gun, majority of them say ZPT-98 itself is based on 2A46M, a few say its derived from China's own 120mm smoothbore gun. Source about Type 96's gun seems to be far fewer(can't even find a designation), the only noticeable difference seems to be the barrel length(L50 vs L48), the ammo should be interchangeable.
Multiple source pointed out that armmor may be the weakest point of any export version of tanks, the article about the recent VT-4 export on guancha.cn mentioned Saudi's M1A2 as an example.
The same article states VT-4's engine is pretty much the same as Type 99A, its output was tuned down for longer lifespan, yet it gives VT-4 top mobility against any competition.
Link repost here: