41. What is the difference between infallible teaching and authentic teaching?

I think the distinction he is trying to make with infallible/authentic is that the infallible teachings are the ones which are on faith and morals, ex cathedra; and the authentic teachings are also true teachings of the Church that we should pay attention to, but which are not infallible. 

Four levels of the teachings of the Magisterium: 
1.  Solemn definitions of the content of Revelation 
2.  Definitive pronouncements related to truths of faith 
3.  Nondefinitive declarations promoting the understanding of revealed truth 
4.  Prudential and contingent applications of doctrine.