Not much difference.<br />
Tanks have 3 main measures in their design that overall determine their quality.<br />
Armour protection: How much protection does it offer it's crew, how much damage it can take and still operate.<br />
Weapon effectiveness: How effective is it's gun and how accurate how quick is it in use and how damaging it is. <br />
Manageability: Tanks acceleration and top speed, it's turret turning speed and speed of turn of its main body<br />
The challenger 2 is better then the leopard in protection but less Manageable the weapon is equal.
Challenger 2, it's got more advanced armour, it's a more up to date design too and it's combat tested, oh and it has tea making facilities which is unique to British armoured vehicles.
You guys have tanks?
Aw, c'mon, thats because we sold you a couple of ours and you re-named them lol.... just kidding, I personally appreciate having you guys as our allies. i visited the UK and it was a blast.
I'm the greatest tank in the universe.
My hot water tank... pressurised showers... nothing better.