Do stellar-mass and super-massive black holes have similar dining habits?
We compare the relationship between the luminosity of the accretion disc and corona in AGN and X-ray binaries in their radiatively efficient (and non-jetted) phases. The observed scatter in the log Ldisc - log Lcorona plane of XRBs is high (~0.43 dex) and significantly larger than in AGN (~0.30). On the other hand, we also find that XRBs and AGN show different accretion rate and power-law index distributions, with the latter in particular being broader and softer in XRBs. Remarkably, once similarly broad photon index and accretion rate distributions are selected, the AGN sample overlaps nicely with XRBs observations in the mass-normalised log Ldisc - log Lcorona plane, with a scatter of ~0.30-0.33 dex in both cases. This indicates that a mass-scaling of properties might hold after all, with our results being consistent with the disc-corona systems in AGNs and XRBs exhibiting the same physical processes, albeit under different conditions for instance in terms of temperature, optical depth and/or electron energy distribution in the corona, heating-cooling balance, coronal geometry and/or black hole spin.