When talking about a lighting fixture, whether it is LED or halogen, the above parameters are taken into consideration. Unfortunately, there is a lot of confusion in this sense and we often end up associating them with an erroneous definition.
Here is the explanation of each parameter.
Lumen:
The lumens represent the luminous flux emitted by the lamp body, they can be real or nominal, we speak of real lumens when we refer to the luminous flux of the LED without obstacles (lamp body, screen, lenses etc.) around it, instead we mean nominal lumens when the LED is inserted in the lamp body, it goes without saying that the nominal lumens will always be lower than the real ones. For this reason, you should always pay attention to what type of value (real or nominal lumens) the manufacturer refers to.
Watt:
Watts are the typical power absorbed by the lamp body, this parameter is also used to calculate how much you will pay monthly for the light, with a KW/h ratio (Kilowatt per hour).
Lumen/Watt:
Lumen/Watt is the ratio between the luminous flux and the typical power absorbed by the lamp body, it is used to calculate the luminous efficiency of the lamp itself. This is the first parameter that should be taken into consideration when referring to how efficient a lighting body is.
Lux:
Lux represents how much light is projected onto a surface. The amount of lux for each workplace is regulated by specific regulations. Lux is usually associated with the uniformity index, which tells us how uniform the light projected on that surface is throughout its extension.
