  Shape/phase transitions in atomic nuclei have first been discovered in the
framework of the Interacting Boson Approximation (IBA) model. Critical point
symmetries appropriate for nuclei at the transition points have been introduced
as special solutions of the Bohr Hamiltonian, stirring the introduction of
additional new solutions describing wide ranges of nuclei. The complementarity
of the IBA and geometrical approaches will be demonstrated by three examples.
First, it will be shown that specific special solutions of the Bohr Hamiltonian
correspond to the borders of the critical region of the IBA. Second, it will be
demonstrated that the distinct patterns exhibited in different transitional
regions by the experimental energy staggering in gamma-bands can be reproduced
both by the IBA and by special solutions of the Bohr Hamiltonian. Third, a
first attempt to obtain a IBA SU(3) level scheme from a special solution of the
Bohr Hamiltonian will be presented.
