Comment by pdpi

Perhaps the most straightforward difference is right in the name — a single-board computer is a whole board. A microcontroller refers to just the IC itself. The thing that's on the article's picture is a dev board for an MCU, not the MCU alone. That's just the chip at the top with the Espressif branding.

Now, if you want to argue that the difference between a dev board and an SBC is kind of vague, I agree on that front. I'd argue that the distinction is mostly the vendor's intent. E.g. if I sell the ICs in bulk and _also_ sell a board with that IC, it's probably a dev board. If I source the ICs from somebody else, only sell the assembled boards, and ship a general-purpose OS with it, it's probably an SBC. With sufficiently powerful hardware (like this thing seems to be), you could use a dev board as an SBC, and that is basically what this article is all about.