Stellar population properties of bulges and discs along with their corresponding distributions. Upper panel: comparison of mean mass-weighted stellar metallicities of the bulges and the discs, colour-coded by bulge stellar masses. The distributions in bulge (disc) metallicities are shown in the right (upper) joint histograms. Each bin in the histogram of the bulge metallicities is colour-coded by the mean bulge mass in that bin. Lower panel: the same as above, but for stellar ages.