Yeah ditto on the confusion! SMTs, I suspect, will be looked at more in HF 25 and probably rolled out then as I think there was a LOT of continual testing but never materialised for a variety of reasons and then Hive Hard Forked.
SMTs would be connected to the Hive blockchain and so would be more secure in the sense in you wouldn't have to rely on 3rd party or custom jsons like on Hive-Engine. However, the speed of development may not be as fast. I seem to remember exyle doing a great tutorial of it back in the day.
To be honest, as a blogger and music producer primarily, it's hard enough to get my head around the DAW, let along blockchain tech and economics 😂