Puzzling difference

In another post, which I don’t seem to be able locate ATM, someone linked to a site where the host goes through how to check for & correct Z axis misalignment by checking for “ripple”. He posted a link to this test model: [U]https://www.thingiverse.com/thing:277394[/U]. I printed the model, 1st in white PETG & again in clear PETG. I noticed quite a difference between the resulting prints. The dimples in the clear PETG print appear to be elongated, while the dimples in the white 1 look much rounder.

Both prints are almost exactly the same dimensions: 20 x 20. The clear 1 is ever so slightly larger, but by less than 0.1mm.

It may appear that there is a vertical line down the middle of the clear dimples, but that’s not the case. It seems to be an odd reflection. Both prints show a “cat’s eye” pattern down the middle of the dimple & I think this may be causing an optical illusion.

In any case, has anyone got any ideas why the dimples on the clear print look twice as wide as on the white 1.

I would guess optics if I were to throw my two cents in.