Thread has IP-based routing, can use 6LoWPAN, has a simpler gateway implementation in border routers, and they've separated out the application layer into Matte

Thread has IP-based routing, can use 6LoWPAN, has a simpler gateway implementation in border routers, and they've separated out the application layer into Matter to allow for easier interoperability and evolution. Zigbee's fine, but it's dated.