The power of a LED depends on the selected operating current. As the operating current can be freely selected and the voltage Uf depends on the current, the electrical power is a variable parameter. Vossloh-Schwabe indicates the current-independent Pel in the data sheet for individual modules. This is why details of the wattage we are used to for incandescent lamps is not sufficient to draw a conclusion on the brightness or quality of the LED. A 4W LED is not necessarily "better" than a 1.2W LED. It may be the same LED under some circumstances, but just operated with different currents.
A better way of comparing the brightness is offered by the lumen information for the light source or the efficiency in Lm/W (lumen per Watt) to compare the energy efficiency.
The brightness of the LED does not increase proportional with higher operating currents but saturation of the semi-conductor takes place. This is why the efficiency of the LED (lm/W) does not reduce with an increasing operating current despite the increasing brightness.