Recent developments in personality research led to the proposition of two alternative six-factor trait models, the HEXACO model and the Big Six model. However, given the lack of direct comparisons, it is unclear whether the HEXACO and Big Six factors are distinct or essentially equivalent, that is, whether corresponding inventories measure similar or distinct personality traits. Using Structural Equation Modeling (Study 1), we found substantial differences between the traits as measured via the HEXACO-60 and the 30-item Questionnaire Big Six (30QB6), particularly for Honesty-Humility and Honesty-Propriety (both model’s critical difference to the Big Five approach). This distinction was further supported by Study 2, showing differential capabilities of the HEXACO-60 and the 30QB6 to account for several criteria representing the theoretical core of Honesty-Humility and/or Honesty-Propriety. Specifically, unlike the indicator of Honesty-Humility, the indicator of Honesty-Propriety showed low predictive power for some conceptually relevant criteria, suggesting a limited validity of the 30QB6.