Vf s the voltage to the LED, I think
Luminous flux is the lumens coming from the LED at a certain power.
R Bin, V bin, a bin code is the code of the LED to describe color, efficiency, tint and so on. Some companies have more numbers and have everything from Vf to typical lumens at a certain power in their Bin codes while others just have the basic color, tint and efficiency in their bin code. Cree R2, R3 and R4 bin LEDs are unreleased LEDs that have better efficiency and maybe lower Vf then the current LEDs. V bin is the unreleased more efficient Seoul P4 LED bin.
Correct me if I said something wrong, I still don't get all the technical terms
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