Relative velocity dispersion and density profiles of FP SIDM runs vs. FP collisionless DM runs. Each row represents a redshift slice. The left panel shows the relative dispersion profile, while the right panels report the relative density profiles (of DM, stars, and total matter, respectively). The dashed green lines report values for rSIDM, while dotted orange lines report values for fSIDM. The shaded area represents the error on the mean of the size regions. Note that the velocity dispersion relative difference has a different radial range compared to the density relative difference (see discussion).