  We demonstrate that for weak flares the dependence on spottedness can be
rather weak. The fact is that such flares can occur both in small and large
active regions. At the same time, powerful large flares of classes M and X
occur much more often in large active regions. In energy estimates, the mean
magnetic field in starspots can also be assumed equal to the mean field in the
sunspot umbra. So the effective mean magnetic field is 900 Mx/cm$^2$ in
sunspots and 2000 Mx/cm$^2$ in starspots. Moreover, the height of the energy
storage cannot be strictly proportional to A$^{1/2}$. For stars, the fitting
factor is an order of magnitude smaller. The analysis of the occurrence rate of
powerful solar X-ray flares of class M and X and superflares on stars shows
that, with allowance for the difference in the spottedness and compactness of
active regions, both sets can be described by a single model. Thus, the problem
of superflares on stars and their absence on the Sun is reduced to the problem
of difference in the effectiveness of the dynamo mechanisms.
