A comparative study was carried out on observation of the growth mechanism of Bi2212 and Bi2201 crystals grown at the surface of a KCl flux by using optical microscopy and XRD. The growth of Bi2212 crystals is typically spiral mediated, while Bi2201 crystals are always layer-by-layer grown. We observed that the Bi2212 crystals grown on a KCl surface at 800-840°C are soft and can be bent freely. No softening was observed for the Bi2201 crystals. The generation of screw-dislocations can be caused by the coalescence of softened crystals. It is suggested that the formation of single, double and multiple spirals in the Bi2212 crystals can be explained by the softening of the Bi2212 crystals. TEM studies revealed abundant dislocation networks in the softened Bi2212 crystals.