Lumens (lm) indicate the total amount of light a lamp produces. It measures the overall light output of the light source, regardless of the environment or distance. A lamp always emits the same number of lumens.
The amount of lumens required depends on factors such as the size and height of the area that needs to be illuminated.
Lux (lx) indicates how much of that light actually reaches a specific surface or area. Lux is measured per square meter and therefore depends on distance, beam angle, and surroundings.
For example: a 10-lumen lamp may illuminate a small cabinet sufficiently, but on a large construction site the lux value becomes too low to provide useful lighting at greater distances.