South London hills

Fuck, I tried that one ... nearly burst my lungs ... had to turn off it at that junction, in order to avoid the walk of shame:

Now, here's where I'm confused, although I've not actually ridden up Vanbrugh Hill and perhaps I should add it to my list of things to do before I die, because I regularly ride up the hill in Greenwich Park and to me it's a walk in the park - actually it's a ride up a hill in the park, but I digress - so how is it that when both hills basically run from the same fairly level road at the bottom to as near as damn it the same level at the top that Vanburgh Hill looks to be twice as high as the hill in the park, huh?