WWIIOL's vehicular system is over 5 years old. RO's is just over one year IIRC.
Of course it's more refined. But...
In WWIIOL, you can't leave your tank.
In WWIIOL, you often can't FIND a tank to drive (even though they are WAY over-represented in the game).
In WWIIOL, the physics model is a lot more refined. It also doesn't help that much because lag and latency can really screw you over.
In WWIIOL, there are STILL hit points. The TANK doesn't have them, but the systems inside the tank DO (in a way. They have a joules damage threshold that, once exceeded, causes the system to stop working).
My hope is that one day RO can afford the physics behind WWIIOL's penetration and damage model (in particular in the damaging of crew department). But the truth of the matter is that RO is FAR better in the infantry department than WWIIOL.
So if you're into Tanking or flying fighters, then WWIIOL is probably a better game for you (better get the best rig in the world to play it though). If you prefer infantry combat (like I do), then RO wins hands down.