This type of fitting is called hybrid, meaning that each end is different. One comes from a French standard (AFNOR) and the other from an American standard (SAE).
A fitting is identified and recognized by:
its visual form. (74° cone, 24° cone, flat, nut shape...)
Gas fitting: This is a cylindrical inch-size thread. Sealing is done by a seal present on the fitting or a BS ring. There is also the conical gas, it is to be avoided for the hydraulic circuits because the sealing must be done with joint paste.
The gas thread of the installation is identical to the BSP fitting.
Metric adaptation: The fitting has a 24° internal cone. Sealing is metal/metal. The adapter thread is metric.
The gas thread of the installation is identical to the BSP fitting.