L is for ultra performance
M is for performance
See my post above, for balanced, preset K should be preferred.
edit - Seems there's conflicting information on that as well
it seems M is for all modes outside ultra performance, so quality/balanced/performance
''With today's
NVIDIA app beta update, all GeForce RTX users can experience the new DLSS 4.5 Super Resolution model in over 400 titles. Simply select "DLSS Override feature - Model Presets" in the Graphics tab, and choose "Latest".
This sets our new Model M across all modes. You can also try out Model L under "Custom", which is optimized for Ultra Performance Mode at 4K. Ultimately, you decide which balance of image quality and performance is right for your PC.''