The luminaire groups define which luminaires in a light scene are connected together (dimmed). Any luminaire of a light scene could only be in one lighting group. Luminaire groups can be managed in the light scenes tool.
You can found further helpful information in the chapter "light scenes" in our DIALux evo manual: Chapter "light scenes"
And in our YouTube tutorial "Luminaire groups for lighting scenes": YouTube tutorial
Control groups can not be created manually and you can't give the control groups own names. The control groups represent the necessary wiring to realize all created light scenes. Luminaires in a control group would connected together (regardless of the light scene). If it is needed the control groups will be recalculated from evo (for example, if another light scene is applied).
A luminaire group in a light scene can internally consist of several control groups. You have to adjust the dimming values for the entire luminaire group only once.