[mdxn]

There is definitely a difference. The problem with the vast majority of "Turing-completeness in X" claims on HN is that they are just logically complete Boolean circuits that are overgeneralized (infinitely tessellated or scaled) for free and cannot handle arbitrarily large inputs. They can only handle constant sized input lengths. To handle an arbitrary input, the circuit has to be resynthesized and created to handle that particular case length. This ends up being a massive leap in computational complexity from constant-time to decidable.

Some of these claims are even wrong since the posters don't bother analyzing whether their suggested generalization technique (e.g. infinite tiling) actually do let you topologically embed every gate and batch of wires into any Boolean circuit you want. This is quite common in 2D side scrollers where you have constant y-height and infinite x length. It just is not possible to communicate all the information you need for a computation from one side of the map to the other. This was the case with Minecraft prior to bidirectional flying machines. You could actually prove that any finite sized "machine" could not communicate an arbitrary distance away (think arbitrarily long Turing tapes) without losing some part of it going off in the distance forever. Hence it was not "Turing-equivalent" unless you used command blocks or gave some overly general infinite tiling capabilities.

Actual descriptions of Turing machines are finite in size/length. These "Turing-equivalent" candidates that keep popping up are not when laid out. This makes it pretty easy to run into uncomputability situations when you try to feed the machines a description of itself and compute some property (like a number = 2x its length). A typical Turing machine would have no problem handling this, though a Boolean circuit would.