What is the difference between Iv (luminous intensity) and F (luminous flux)?

Iv (luminous intensity) refers to the brightness per solid angle in a certain direction; its unit is "cd" (candela). As the LED has been used as a display light source, the brightness viewed from its front has been significant. For that reason, Iv is most widely used as the unit of the display light source LED.

F (luminous flux) refers to a total quantity of light emitted from the light source; its unit is "lm" (lumen). It is used to represent the brightness of power LED, etc.