  Ultra-high-energy cosmic rays (UHECRs) refer to cosmic rays with energy above
10^{18} eV. UHECR experiments utilize simulations of extensive air shower to
estimate the properties of UHECRs. The Telescope Array (TA) experiment employs
the Monte Carlo codes of CORSIKA and COSMOS to obtain EAS simulations. In this
paper, we compare the results of the simulations obtained from CORSIKA and
COSMOS and report differences between them in terms of the longitudinal
distribution, Xmax-value, calorimetric energy, and energy spectrum at ground.
