  We present a detailed multi-wavelength analysis of two short Gamma-Ray Bursts
(sGRBs) detected by the Neil Gehrels Swift Observatory: GRB 160624A at
$z=0.483$ and GRB 200522A at $z=0.554$. These sGRBs demonstrate very different
properties in their observed emission and environment. GRB 160624A is
associated to a late-type galaxy with an old stellar population ($\approx$3
Gyr) and moderate on-going star formation ($\approx$1 $M_{\odot}$ yr$^{-1}$).
Hubble and Gemini limits on optical/nIR emission from GRB 160624A are among the
most stringent for sGRBs, leading to tight constraints on the allowed kilonova
properties. In particular, we rule out any kilonova brighter than AT2017gfo,
disfavoring large masses of wind ejecta ($\lesssim$0.03 $M_\odot$). In
contrast, observations of GRB 200522A uncovered a luminous
($L_\textrm{F125W}\approx 10^{42}$ erg s$^{-1}$ at 2.3~d) and red ($r-H\approx
1.3$ mag) counterpart. The red color can be explained either by bright kilonova
emission powered by the radioactive decay of a large amount of wind ejecta
(0.03 $M_\odot$ $\lesssim$ $M$ $\lesssim$ 0.1 $M_\odot$) or moderate
extinction, $E(B-V)\approx0.1-0.2$ mag, along the line of sight. The location
of this sGRB in the inner regions of a young ($\approx$0.1 Gyr) star-forming
($\approx$2-6 $M_{\odot}$ yr$^{-1}$) galaxy and the limited sampling of its
counterpart do not allow us to rule out dust effects as contributing, at least
in part, to the red color.
