Lumens doesn't mean what people really think it does. There's a conversion scale called luminous efficacy which converts watts of electromagnetic radiation to our perception of how bright it is.
When I say watts, I don't mean the watts powering the lamp, but the watts of energy in light leaving the lamp. Luminous efficacy (measured in lumens per watt), peaks at around 555nm and tapers off on both ends of the visible spectrum.
This means 1W of 555nm light will be given a much higher lumen rating than 1W of say 660nm light, even though the power of light itself is the same. This is simply because we see 555nm light as significantly brighter than 660nm light. It sort of makes lumen ratings an unreliable measurement, especially for leds. This is also why it doesn't matter why 630nm leds are often brighter than 660nm. They may be brighter, but that doesn't mean they have more radiant flux.
In order to give a number for lumens, they have to do a complete spectral analysis of their lamp and run a computation against the luminous efficacy curve to get the lumen value, a single number to describe how bright the light is to us.
I guess if you're comparing leds with the same wavelength, having a higher lumen value does mean it's more efficient.
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