Magnetic core and compositions
If two cores are made with different materials and the same geometry and both have the same AL, the only way this is possible is that their permeability is the same, you can see it in the formula you wrote above,

and the manufacturer declares that the permeabilities they can be the same, look at the table of &quot;key characteristics&quot;. Refers to relative permeability for example &quot;14u&quot; is equal to 14 times the permeability of vacuum.