Relative (left panel) and absolute (right panel) differences of spectral line parameters measuredin different ESPRESSO echelle orders as a function of wavelength, EW, and the distance from the center of the spectral order. The boundary wavelength region (at ~5250 Å) of the blue- and red-arm detectors is indicated by a gray rectangle. Line properties have been measured with ARES with a fixed S/N for each order. The linear regression of the data is shown as black lines.