The Classic and new apps handle the country/region that users are located in differently. For the Classic app, the globe is essentially divided into three sections similar to the International Telecommunication Union regions. As Samsung has a worldwide presence, the availability of devices, SmartApps, and features is restricted much more granularly. This helps curate more relevant experiences in addition to assisting with things such as compliance to local regulations.
The overwhelming majority of Classic users won’t notice a difference while a small subset of users might notice a different set of SmartApps available for installation. Most of these users are located outside of areas where the SmartThings v2 (2015) Hub was released which was limited to the UK/Ireland and Canada/USA.