Comparison of the 2 μm and 4 μm morphological properties of the SMGs and both field samples. We compare the difference in M₂₀ parameter between the F444W and F200W bands ($M_{20}^{\mathrm{F}444\mathrm{W}}$ − $M_{20}^{\mathrm{F}200\mathrm{W}}$) with dust attenuation (A_V) in panel a). In panel b), we further compare the difference in RFF between the F444W and F200W bands (${\mathrm{RFF}}^{\mathrm{F}444\mathrm{W}}-{\mathrm{RFF}}^{\mathrm{F}200\mathrm{W}}$) with the difference in Asymmetry (A^F444W − A^F200W). Finally, we plot the difference in M₂₀ between F444W and F200W ($M_{20}^{\mathrm{F}444\mathrm{W}}$ − $M_{20}^{\mathrm{F}200\mathrm{W}}$) with the difference in Concentration (C^F444W − C^F200W) (panel c) and the difference in RFF (panel d). All four panels indicate the SMGs are much more structured than either field population, with less uniform light distributions in the F200W band compared to F444W, in contrast, the field galaxies show minimal wavelength variation.