The process of tooth eruption consists of two phases, active and passive. While the distinction is unequivocal, the mechanism is ambiguous. This article compares and contrasts altered passive eruption (APE) and active secondary eruption (ASE). Although these phases present with similar clinical manifestations, each has its own etiology, physiogenesis, and pathogenesis. Furthermore, the differential diagnosis between the two, and that between other mirroring conditions, is essential for arriving at a definite diagnosis and correct treatment strategies, which may be similar but have different consequences. This article concludes with two case studies that show the management of APE and ASE, highlighting the treatment similarities and differences that are dependent on the specific etiology.