You can find the different parameters at Calculation objects -> Calculation objects -> Calculation parameters.

The arrows in the icons of a calculation parameter shows the direction where the light comes from. The name of a parameter refers to the orientation of the surface.

Horizontal illuminance:

Perpendicular illuminance:

The perpendicular light which strikes on a horizontal surface.

Perpendicular illuminance(Adaptive):

The perpendicular light which strikes on a horizontal surface. The difference to "Perpendicular illuminance" is that for this surface the number of calculation points is determined automatically depending on the minimum and maximum values. The calculation is more accurate considering these values.

Vertical illuminance:

The light which strikes on a vertical surface.

Unified Glare Rating (UGR):

Is used for calculation UGR values.