It feels like the documentation is badly broken. I have experienced this firsthand that it is almost impossible to decide what to buy just by looking at the parts themselves.
I have created and cancelled two orders already after going through tens of forum posts and then realizing that the parts are incompatible.
To add to the confusion, some core modules like the M5Go Lite Kit and M5go Starter kit has same "Included Parts" sections, but are different in price. See the two included screenshots. The title of the tab will tell you exactly which product the screenshot is for. The left image is of IoT Starter Kit, the right one is M5G0 Lite. Ofcourse both of them have six Units as written, but the photos show a different story.
Things like these are all around the site.