AFAICT the Espruino and Tessel are slightly different. The Espruino's focus seems to be providing an ultracompact, low-power, very simple JS-powered Arduino, w

AFAICT the Espruino and Tessel are slightly different. The Espruino's focus seems to be providing an ultracompact, low-power, very simple JS-powered Arduino, which (with physical adapter) could be used with existing Arduino shields. The Tessel seems to be focused more on the interfacing-with-the-internet side of things, with built-in wifi. I think there's plenty of room for both, and it's exciting to see continued efforts towards making it easier to bridge the gap between embedded devices and the software world!