  The properties of several types of Q-stars are studied and compared with
their flat space analogues, i.e. Q-balls. The analysis is based on calculating
the mass, global U(1) charge and binding energy for families of solutions
parametrized by the central value of the scalar field. The two most frequently
used Q-star models (differing by their potential term) are studied. Although
there are general similarities between both Q-star types, there are important
differences as well as new features with respect to the non-gravitating
systems. We find non-solitonic solutions which do not have a flat space limit,
in the weak (scalar) field region as well as in the opposite region of strong
central scalar field for which there does not exist Q-ball solutions at all.
