The response of the ATLAS Tile Calorimeter to pions and protons in the energy range of 20 to 180 GeV produced at CERN's Super Proton Synchrotron (SPS) H8 test beam line has been measured. The experimental setup allowed to measure the longitudinal development for pion and proton induced showers up to 20 nuclear interaction lengths. It is found that pion showers penetrate deeper in the calorimeter than the proton induced ones. However, protons induce showers that are wider laterally to the direction of the impinging particle. Including the measured total energy response and the resolution, all observations are consistent with a higher electromagnetic energy fraction in pion induced showers. The data are compared with GEANT4 simulations using several hadronic interaction models.