We present a comparative study in terms of structural properties deduced from X - ray diffraction diagrams between YBa2Cu3O7 (YBCO) thin films fabricated on SrTiO3 (STO) single crystal substrates and bicrystallines substrates with a symmetrical tilt angle of 24 degrees. Periodic Lattice Distortions (PLD) have been observed around different Bragg peaks in YBCO thin films deposited on STO bicrystals while only diffraction peaks have been measured in the diagrams corresponding to the YBCO thin films deposited on STO single crystal substrates. Only in regions situated a 3.5 mm at both sides of the grain boundary the PDL have been investigated. Scans along different (h, k, l) directions allow us to conclude that the qPLD vector associated to the distortion is along the (h,-k,0) direction. However, we found that the amplitude of the components of the q
PLD vector depend on the Bragg peak chosen. We believe such a result indicates that we have not a PDL with a simple q
PLD vector. In this line, other (h, k, l) directions must be investigated to deduce the exact origin of the q
PLD vector. Nevertheless, independently on the q
PLD vector associated to the PLD, we believe that such a distortion in the lattice is a consequence of the stress field induced by the grain boundary in the YBCO thin film deposited on the bricrystal.