The GT3 has gold-plated parts, USB-C charging, the magnetic tool at the bottom, and can be used with or without Zeus ARCPods. The Zeus ARC S Hub does NOT have gold-plated parts (stainless steel chamber, zirconia vaporpath), micro-USB charging, NO magnetic tool, and can ONLY USE Zeus ARCPods (it will not work without them). Everything else (including the Hub) is the same.