Fretting wear, encompassing impact, sliding, and combined impact-sliding modes, likely occurs between alloy 690TT tubes and their support structures within nuclear steam generators. However, the wear behavior and underlying mechanisms for these distinct motions remain inadequately understood. This study provides a detailed clarification of the similarities and differences between these motion types. Results demonstrate that the tube motion trajectory significantly influences fretting behavior, wear mechanisms, and microstructural evolution. Under impact-sliding motion, the coefficient of friction exhibits periodic variations showing a characteristic markedly distinct from other motions. This motion generates an irregular wear scar contour and produces the highest wear volume. Fatigue wear dominates uniquely under pure impact conditions, whereas oxidation and material transfer intensify during sliding and impact-sliding motions. Dynamic recrystallization (DRX) within the subsurface and surface oxidation are notably limited under impact. Conversely, the amorphous-to-crystalline transformation of the oxide layer and the DRX process are substantially enhanced under sliding and impact-sliding conditions. These findings provide valuable insights for the structural integrity assessment of heat transfer tubes.