i think charlie being shorter than elden has something to do with how in that one shot where they're on a sidewalk, they're standing on a handicap accessible ramp. charlie's standing on the lowest point of it while elden is standing where the ramp joins the rest of the sidewalk, meaning he's standing on slightly higher ground compared to charlie.

a lot of this has to do with looking at comparative heights while standing on certain raised surfaces, because if the surface is uneven it may cause a weird change in their height just by eyeballing them. when charlie and elden are standing on even ground, elden is clearly at least an inch shorter.