Three Dimensional Maneuver speed is how they conquer the height difference and allows them to attack only real weak point of a giant, the back of his neck.
The result is that you have what can only be described as steam powered giant spider attacking with swords. Although they are not superheroes, so when they err results are both fatal and very messy.
So far, this feature speeds Three Dimensional Maneuver escaped a game adaptation for Attack on Titan. To be fair, this is because it is actually a difficult problem and most publishers these days are wary of deviating from the functionally standardized norm.
Omega Force has done the smart thing here though and apparently tested on basic mechanics in various prototypes carefully beforehand and it shows.