# Device Handler (classic) vs Device Plugin? **URL:** \ **Category:** Writing Device Types\ **Created:** [March 11, 2019, 4:51am UTC](https://community.smartthings.com/t/device-handler-classic-vs-device-plugin/157232 "2019-03-11T04:51:03Z")\ **Posts on this page:** 1\ **Showing post:** 2
**Author:** ![JDRoberts](https://yyz2.discourse-cdn.com/smartthings/user_avatar/community.smartthings.com/jdroberts/32/56577_2.png) [@JDRoberts](https://community.smartthings.com/u/JDRoberts)\ **Post date:** [March 11, 2019, 5:24am UTC](https://community.smartthings.com/t/device-handler-classic-vs-device-plugin/157232/2 "2019-03-11T05:24:36Z")
There is no guaranteed backward compatibility between classic and the new app. There are features that have been removed altogether. And each version of the app has a feature called “smart home monitor” but they are completely independent of each other and work somewhat differently. There are other incompatibilities as well. See the following thread for that discussion (the title is clickable link). > [@SPECIFIC differences between "SmartThings Classic" (the V2 app) and “SmartThings (Samsung Connect)” (the V3 app)](https://community.smartthings.com/t/specific-differences-between-smartthings-samsung-connect-and-smartthings-classic/124870): > > this thread is intended only as a listing of specific differences between the two apps, not for complaints, suggestions, discussions of design philosophy, bug reports, questions about migration, joke memes or anything else. Just individual feature differences. We originally used the abbreviation STSC for “SmartThings (Samsung Connect)”, but that never caught on, so now we are calling it the V3 app since it came out with the V3 hub. The V3 app is changing rapidly, so feel free to edit this as needed. The official knowledgebase FAQ is at the following link. Read it. wink[https://support.smartthings.com/hc/en-us/articles/360000114006-New-SmartThings-app-FAQ](https://support.smartthings.com/hc/en-us/articles/360000114006-New-SmartThings-app-FAQ) The “how to” official articles for the V3 app are at the following link: [https://support.smartthings.com/hc/en-us/categories/115…](https://support.smartthings.com/hc/en-us/categories/115000465506-SmartThings-App) As far as the new development platform, no guaranteed backward compatibility there, either. But it’s not finished yet, so all you can do now is test stuff with it. And the last time I looked, one of the things that was unfinished was any way to communicate with A zigbee or Z wave device connected to the hub. That is, they have not yet released the details of whatever the new equivalent of device type handlers will be for those protocols. --- _[View the full topic](https://community.smartthings.com/t/device-handler-classic-vs-device-plugin/157232)._