I can not see any differences between the two switches physically at least. It looks at least on paper to have more range in how far it can share the z wave signal.
The newer one uses z-wave plus.
12723 is the addon switch or auxiliary switch for the GE 12 series smart switches and dimmers. To the best of my knowledge, they will also work with the new 14 series Z-Wave Plus switches and dimmers.
However, your comparison is mixing master switches with add-ons. Be careful as the add-ons do not connect to ST at all. They are wired into the masters for 3-way and up to 5-way operations.
Both series however, are the same physically. Z-Wave Plus is the new standard. Has the double click function which can be useful for getting more out of your switches such as calling scenes or anything assignable that you can think of…
The 14294 is the dimmer
1571
Sorry, I couldn’t help myself.
Hope you enjoy your Home Automation journey. It’s addictive. 
1 Like
yeah sorry 12724 is what mean i will change the post