CrySPY uses pyxtal in normal molecular crystal structure generation mode (struc_mode = mol). The molecules are arranged to fit a point group at a selected Wykoff position in the space group to keep the symmetry. (Sometimes it takes a long time to generate.)
In mol_bs mode (bs means break symmetry), dummy atoms are placed in Wykoff positions as in ordinary crystals, and then the dummy atoms are replaced by molecules without considering symmetry and rotated randomly. The structure generation is relatively fast.