The Sony PlayStation 5 has been changed slightly. The original model has a larger cooler on the machine and the new one has made this smaller. The goal is to reduce the cost of the machine at the expensive of slightly warmer operation.
Consoles are generally sold bellow cost and make it up with games sold. So reducing the cost of the console is a questionable business strategy.
Other consoles historically have introduced new models instead of tweaking the original model. Sony is experiencing problems producing enough consoles to meet market demand.