VM's "up to" lets them off the hook for congestion in the Internet. Area congestion (which they eventually fix) is considered by them as a fault when a threshold is reached.
BT's (and the others using the copper last mile) "up to" means something else. It means that your speed depends on how far you are from the street cabinet and whether or not your wires are of aluminium substance rather than copper. These are physical constraints that result in your minimum speed offer. VM does not suffer this constraint.
So the same term "up to" then creeps into discussions, covering the same sentiment to users discussing the two systems, but actually meaning very different situations.
On latency, my BT Infinity 2 latency is worse than my VM 200/12 latency. That's prolly due to the aluminium wires that go to the street cabinet, not to mention that BT at 55/10 can't come close to VM's 200/12. What I really object to with BT Infinity is having to pay the same price as the neighbour with copper wire who gets the 76/20. BT are total sharks sweating the copper/aluminium "asset" and milking the customers in areas where VM don't supply.
BT Infinity 80/20 (running @ 48 meg)
My advice is at your risk.