The male and female surface type is very simliar to the tongue and groove surface type and they should be matched to each other.
The different between M&F and T&G is that unlike T&G, M&F’s ring and groove extent upto the inner bore of the flange.

Additional Information
Compared with FF and RF, RTJ, T&G and M&F provide stronger connection and better fit. However, they are more expensive than FF and RF, and commercial availabilty can be limited since FF and RF are most commonly used in the market.
In addition, when using T&G and/or M&F, the complexity of designing the piping system may increase since they have to be matched.
Same surface type should be used and it is not recommended to assemble with a different surface type (e.g., assembling RTJ with RF).
When not using the same surface type, a gap may exist in the gasket part and a trustable connection cannot be guaranteed, and thereby a leakage may occur.