Both are on black PCB, and both have 1 MB flash memory (I checked with a sketch).
The one marked "ESP-01S" does not have a red power LED, only one larger, blue LED. It also has far more chip capacitors than the other one. And using the Arduino IDE, addressing LED_BUILTIN does not work. I found the LED to be connected to GPIO2, and not the usual GPIO1 = LED_BUILTIN. Loosing the red LED suits me fine, as I am working on a battery powered project and would remove it anyway.
The other black module is marked "AI-Cloud inside", and is closer to a "classic" (blue) ESP-01, it is similar but not identical in layout or number of chip component to some blue ones I have lying around.
I tried both to google for more information and search this forum, without much luck.
Has anyone else noticed this, and does anyone have knowledge about more differences between the versions than the blue LED?
Photo of the two versions: