In the 64 pad grid, North falls between Bhallat and Soma (N4 and N5), East between Mahendra (Kulish) and Surya (E4 and E5), South between S4 and S5 and West between W4 and W5. Vishwakarma Prakash (page 124) gives the 64 pad koshtak vastu mandal for temples and idol installation and describes the 81 pad layout separately, which the teacher showed as proof.
Zones remain the same in both grids; what changes is the order of the padas: two padas make one zone, sometimes as two half padas and one full pad. For precise door and room locations in a house, use only the 81 pad vastu.