The original SmartClient (now known as 'SmartClient Classic Edition') was built on the old, Windows Desktop specific VSTO technology. VSTO technology supports Excel Desktop versions including Office 2010.
Microsoft is focusing their efforts on a new Office Add-in Framework and it is their strategy to pursue this new framework and drop mainstream support for VSTO.
With the increased popularity of cloud based Office suites and Apple devices in the workplace, we have chosen the same path and have built the new SmartClient apps on the future-proof, cross-platform Add-in Framework. This platform enables add-ins to run on Office for WIndows Desktop, Office Online, Office for Mac and eventually on Office for Mobile devices. We have rebranded the new Apps as CloudExtend Excel for NetSuite and CloudExtend Excel for Salesforce.
We are continuing to support the Classic Edition for our customers while also giving them access to the new CloudExtend editions at no extra charge. We expect to reach full feature parity between editions in early 2019 (at present there are minor differences between the two).