How does "treated as if moving the same distance" mean anything other than they move the same distance?
People used to get this wrong in DBM as well. It's a rather subtle distinction between "move" as in distance you actually move and "move" as used in a wargames sense of how far you are allowed to move, often called "movement allowance" in game rules, but carrying the physical sense of "speed".
I don't think it means exactly "they move the same distance" and it does not mean "it is given the same movement allowance". I'll explain what I think it does mean by way of an example:
Consider a column of 2 elements of chariot Cv, A and B with A in front. Lets say it has turned right 45 degrees and stopped straight after the wheel, so the rear right corner of A is touching the front edge of B somewhere near its left hand end.
Next bound, A advances straight ahead 240 p.
If B "moves the same distance", its front left corner will not reach A's rear left corner. There will be a gap between the elements. So it certainly does not mean "they move the same distance".
What you are supposed to do is wheel B at the line of the original wheel and then butt it up against the rear of A. In reality, it has moved further than A. However, it is "treated as if moving the same distance", i.e. treated as having moved in this case 240p. THe max move distance for Cv is 240p, so this is OK.
Now suppose B is Kn. The max move distance for Kn is 200 p . If B followed A in the column, it would count as having moved 240p. That exceeds its maximum move, so it is not legal. To move this column, A moves 200p and B is butted up against its rear. B has actually moved about 220p, but is treated as moving the same as A, i.e. 200p. This is its max move distance so this move is allowed.
"Treated as if moving the same distance" does not mean they have the same movement allowance. If you have a column of LH in front and Art(S) behind, it does not allow the Art(S) to move at LH speed. It constrains the LH to move at Art(S) speed, but allows the Art(S) to exceed its normal move enough to catch up the extra distance caused by the kink.