Well, there is a type of ammunition used as that kind of factor for vehicles if we want to be picky, which is easy explanation for range, penetration and AoE differences bewteen StuG and P4 for example.
Training is still a factor as sniper also uses mosin and shoots further then conscripts or guards.
Pretty much the only weapons that are consistent across the faction are the ones that are exclusively for one singular unit.
And since CoH is arcade RTS and not simulator like MoW, there is absolutely nothing wrong with inconsistencies as long as desired balance of the unit is achieved. What weapon looks like, who uses it or how its named couldn't be any less relevant here is balance is end goal.
Its not like elchino is wrong there.
Of course you can go deeper into the realms of ammunition but I think that's unrealistic to assume for a casual player, even one that's slightly into the genre.
A sniper by definition is better at using the weapon. Hardly a prime example.
As for the others it COULD be boiled down to making their shits count. The damage isn't as key as the DPS. The better solider, despite using the same gun, can kill quicker. At the heart of it that's not unreasonable.
A cannon however, having them preform radically different can lead to confusion to the avid ww2 "fan" (bad term Givin the death but idk what else to call it) but not someone all up in here asking for hard stats...
Like someone who knows the war might be confused that the pak43 deals 320 damage as an emplacement, 300 as an elefant, 300 as a JT but now with more range and 240 on the KT but with less range....
Or that the ZiS3 on the zis has less pen and damage when mounted on the T70 chassis.
I feel that it's simply more complicated than it needs to be. Obviously at THIS point there is no going back, but I almost feel that it would be easier in a sequel (and better for the casual player) if performance is normalizes and price is the defining balancing factor (that and things like ROF and accuracy which can be accounted for by crew conditions)
Its all simantic and theory now so I won't persue the discussion but I can understand the infantry variable but less so the vehicle one simply due to perception.
The player base is shrinking and its only hard fans left, I'd say in the future having the game simplified and more predictable and transparent will help the games health by allowing casual players to get deeper into the game without going out of their way