  The energy spectrum of ultra-high energy cosmic rays (UHECRs) provides
essential information on the most energetic phenomena in the Universe. Beyond
EeV energies, the Telescope Array and Pierre Auger Observatory have the largest
exposures to UHECRs ever accumulated in the Northern and Southern hemispheres,
respectively. The results show independently a steepening of the energy
spectrum above a few tens of EeV. However, the comparison of the spectra shows
differences that are not explainable in terms of an overall uncertainty on the
energy scale used to reconstruct the extensive air showers. The differences are
also observed in the region of the sky covered by both instruments, where the
spectra should be in agreement within uncertainties when directional-exposure
effects are accounted for. For this contribution, a working group from both
collaborations examined these differences considering the energy-dependent
systematic uncertainties. A special focus is given to the characterization of
the spectral features, which provide an accurate tool to enhance our
understanding of the comparisons.
