The essential difference between these two groups lies not in their attachment to the traditional Mass, but in their public judgment on the causes of the crisis. Canonically recognized traditional communities continue, by virtue of their statutes, to institutionally accept the Second Vatican Council and the liturgical reforms. They may criticize certain excesses or interpretations, but they do not contest the principles or the legitimacy of the reforms.
The SSPX, on the contrary, considers that several conciliar teachings, particularly on religious freedom, ecumenism and collegiality, as well as the liturgical reform itself, constitute deep causes of the crisis and must therefore be subjected to doctrinal criticism.