Serial Experiment Lain Layers vs Episodes?

I was looking into the anime Serial Experiments Lain and came across that the show episodes are called layers but when I ran into the show i noticed that theres two versions or something? theres the original 13 episodes that are about 23 minutes long but i also found a version called layers that are only 20 minutes long. Just curious if anyone knows the distinction between the two.

Serial Experiments Lain seems to come up a lot in cyberpunk media.