1. Lumens ‌
The general unit of luminous flux, representing the total brightness emitted by a light source (such as a bulb or LED), does not take into account the light loss during the projection process. Often referred to as "light source lumen".

2. ANSI lumens ‌
The projection luminance standard formulated by the American National Standards Institute (ANSI) is measured by the nine-point method: the average illuminance of nine points on a 60-inch screen is taken and combined with the projected area to calculate the luminance value.

3. Differences in measurement methods and results
Lumes： Only testing the original brightness of the light source and ignoring the influence of lens attenuation and ambient light can easily lead to false overestimation of the result.

ANSI lumens:  Strictly stipulate the size of the curtain and the projection distance, and calculate the average value of nine points.

Lumen is a universal unit of brightness, while ANSI lumen has established strict testing standards for projection scenarios, which are closer to the actual usage effect.