The difference between critical theory (and postmodernism generally) and social justice is the belief in universal values. Believers in postmodernism don't accept universal values. They see every conflict as a power struggle, devoid of moral truth.

Broadly speaking, social justice advocates, or at least those described in the article, and caricatured by the Channel 4 interview, do have a universal value, namely equality of outcome.

The truly destructive force, again shown in that interview, is that logic is not universally valued. If equality of outcome can be obtained while posturing and arguing strawmen, then go for it.