Stereo vs Mono audiophile headphones

Help me understand the difference between non stereo headphones and stereo variants… I’m looking at two different sets - the Audeze LCD 2 and the Meze 99 classic v2. I understand how stereo works but the Audeze while being able to run left and right to each cup is not considered stereo head phones (states stereo is not “built in”). How is that? Does this mean that the drivers themselves are not connected to each other physically? Cause that would be the same case for the meze 99’s which are stereo headphones.