It’s not only about the light output, but rather the ratio of output (light) and consumption (watt/joule). The higher the output and the lower the consumption, the more efficient the LED. How much light an LED module can produce also depends on the lifespan, colorfastness and color quality.
The term efficiency originates from the traditional lighting market and has been changed from lumen/watt to P.A.R. μmol/watt for horticulture. The standard holds some truth but has largely become a marketing story because certain spectra are made for the highest efficiency but are scientifically not in line with the results of the plants and/or different cultivation goals. The highest efficiency can be achieved when the red-blue spectrum is applied. It has also been proven that this is not the best spectrum for every crop.
check here our video about the efficiency: