Here's a link on 1st-line that elaborates: Le'Lit PL041TQE - PID Home Espresso Machine. Among the new features:

Now features a PID unit! The PID is the newest innovation from Le'lit- it allows the user to change the temperature of the coffee boiler to allow the water temp most closely perform a superior and more consistent espresso extraction.

As discussed countless times in the context of "Should I PID <insert single boiler name here>?" topics, a PID eliminates the boiler's thermostat deadband so temperature is tightly controlled, but it doesn't do anything you can't accomplish manually with temperature surfing. So your "upgrade" would be one of convenience and greater (automated) consistency, but the absolute espresso potential won't change.

PS: For those following this thread, also see Howard's reports on Pulling shots with Lelit PL041.