Main difference is an Apple watch with Siri is tied to your phone and has access to all the associated apps/features. I can use my Apple Watch to start a timer, send a message, add a reminder to my calendar, play a new music track in a non-Apple music app, etc etc. Pretty much all major iPhone apps support some form of watch integrations.

The whole problem with this device is it has all this hardware technology but no software/apps to back it up. No connection to your phone apps, no connections to your existing subscription services or anything other than the (very) limited built-in features.

This same hardware tied to a phone and its apps would be a whole different thing… and a whole lot more useful.