Here's a video and diagram I made that explains the difference between all three program in the most simple way possible; while using cats, so anyone can understand the difference. Also I will explain using a walk through each procedure at the airport with each security service program and explaining why you would want to sign up for that program.

Amid long waiting lines at airports, some travelers say they’re avoiding the worst delays by using TSA PreCheck Touchless ID. Airports continue to struggle with longer security lines during the partial government shutdown,

A partial shutdown affecting the Transportation Security Administration is causing long airport lines and flight delays across the U.S.