The 4th generation Smart Lock is available in the standard version and the Pro version. We have summarized the differences between the two variants for you:
The Smart Lock Pro (4th generation)...
... is available in black and white. The upper segment (ring) is made of aluminum.
... includes a built-in Wi-Fi module. You don't need any other accessories to control it remotely.
... supports Matter via Thread.
... includes Power Pack for optimal power supply.
The Smart Lock (4th generation)...
... is available in white and its upper segment (ring) is made of white plastic.
... remote access is available via the Nuki Bridge or via Thread (separately available).
... supports Matter via Thread.
...comes with 4 batteries. The Power Pack is separately available.
An overview of the different product versions can be found here.