When you are taking a look at lumens, you will come across a concept called ANSI lumens as well. Lumen is the generic term that is used to represent the brightness levels that you can get from a projector. However, the projectors that you can purchase from the market along with the ANSI lumen rating. ANSI lumen is the standardization that is given to lumens by the American National Standards Institution. It is introduced to ensure that the projector manufacturers are following standards at the time of defining the lumen output that you get.