Difference between one and two-piece fitting

In the one-piece fitting, the shank and ring nut are pre-assembled forming a single piece.

In the one-piece fitting, the outer diameter of the ring nut is usually larger than that of the two-piece fitting.

The two-piece fitting is made up of the ring nut, which - in a hydraulic flexible hose - is inserted into the hose up to abutment, and the shank which is lubricated before being inserted.