First let’s remember that Power (Watts) = Voltage x I(Current)
LED plant lights are grouped by the current (Amps) of the diodes within the light. 1 watt diodes generally run at around 0.35 Amps, 2 watt diodes run around 0.5 Amps and 3 watt diodes run around 0.7 Amps. Diodes are not maximized with current so that the manufacturer can increase the lifespan, reduce the heat output, and supply a better grow light. In addition, different color diodes have different wavelengths and require a different supply voltage for the specific wavelength. The red and orange wavelengths require around 1.8-2.7 Volts and the blue and violet wavelengths require 2.7-3.5 Volts. Hence, following our W = V x I equation, a 3 watt red diode may only have a power draw of 1.5-2.0 watts and a blue diode may only have a power draw of 1.8-2.5 watts. That is why we have the stated wattage of the light and the actual power draw. Hence, the 600 Watt grow light has 200 x 3 watt diodes but the actual power draw is 480 Watts. Some LED companies do not publish the actual power draw. Be careful of these companies and make sure you make an apple to apple comparison when it looking for the right LED for your given grow space.