An LED makes photons (light) and the lens, reflector, etc...are what focuses it. A low transmission lens (el cheapo plastic "clear" lens for example, absorbs some of the light. A reflector with a large hole for the LED board, etc, can reflect light back into the flashlight's body. Some unfocused light spills out and hits the bezel, etc.
The LED lumens are what the LED itself is emitting. Out the Front (OTF) lumens are what is thrown at your target....IE: What's LEFT of the LED lumens by the time they get out of the flashlight.
Some makers are quite honest, but that's not the same as quite accurate. There's a body that publishes test methods for measurements, ANSI, and they have standardized the way the measurements are taken. Some companies simply say the ANSI lumens are whatever the LED chart from CREE, etc, says is the maximum output...and double or triple that if a competitor gets the same idea.
We have people in this forum who measure the output to see how close it is. For the major makers (not the major fakers), the ratings are about right.
Lux = Lumens per Square Meter.
So, if you have 1 lumen, and spread it out over a square meter...you'd have 1 lux of illumination. (You can't SEE a lumen. You can see lux, as the light that reflected back to your eyes. The brighter it looks to your eyes, the higher the lux)
Some beams are tightly focused, so the beam angle is small, and the cone of light coming out is narrow. You see a small dot of light off in the distance.
Some beams are widely focused, so a fan shaped swath of area is lit up all at once....you see every thing in front of you in one shot.
If the beam has spread, based on the distance, to a 1 square meter sized circle of light on your target, and you had 100 lux on that small target....
...with a wider beam, say 2 square meters in area on your target, you'd now have 50 lux on that larger target...with the same lumens.
So, the beam angle has an enormous impact on the size of the beam at any given distance...and, the size of the beam's spot on a target at any given distance, for a given lumen output, has an enormous impact on the resultant lux.
Otherwise, its like a bar conversation about not understanding why a motorcycle with 100 horse power is so much faster than a tractor trailer with the same 100 HP.
So the LED is going to perform VERY differently depending upon what its IN. So, yes, the surefire mentioned is not a good choice if you want to light up a tree 100 meters away....but there are LED flashlights that can light up trees closer to a mile away....they're just not sold by SF for example.
There are LED with yellower tints, cool white tints, etc...and, yeah, angry blue is for the check out line specials...but, those are not state of the art shall we say.