Connecting rod "offset"?

yellow rose said

Yes, those rods don't have an offset because they are pin guided rods. You have to compare apples to apples. A non pin guided rod has offset.

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Thanks very much. This particular idea is all new to me. Is there anything different in the piston design if it is used to guide the rod (via the pin)? I'm just trying to figure out where the forces go and how that effects things....if the rod drifts forward or backwards, something has to restrain it. (Which I assume is the reason for the washers Kooser is referring to...)
Or is 'pin guiding' just what is keeping the rod in an upright position, and the rod big end still works back and forth between the side of the journal and the other rod?