In the present paper, we discuss the differences that underlie a topic of current intensive research and debate, e.g., the appearance of phase transitions and shape coexistence in atomic nuclei. Besides a formulation of the basic differences, we discuss on one hand some typical examples of shape coexistence (near the Sn and Pb closed shell regions) and, on the other hand, of phase transitions. The present discussion should allow a more transparent way to analyze nuclear structure changes in particular mass regions.