Samsung Galaxy SmartTag+ (or SmartTag Plus, to be more SEO friendly) is a Bluetooth tracker is an improved version that boasts additional technologies to enable more accurate tracking.
In addition to Bluetooth Low Energy, it has ultra-wideband (UWB) radio that will allow it to pinpoint the location with greater accuracy when you are near a SmartTag+ tagged item.
Unfortunately, though, it is this UWB that limits the new Galaxy SmartTag Plus use to more expensive Galaxy phones that are equipped with UWB technology.
At this point, Galaxy devices that support this new Bluetooth tracker includes Galaxy Note20 Ultra, Galaxy S21+, Galaxy S21 Ultra and Galaxy Z Fold2.
The SmartTag Plus further touts augmented reality (AR) technology that can visually show you where your missing item is using your smartphone camera.
If you think of the tag as a scale, the Bluetooth would be the centimeter scale and the UWB would be millimeter scale that lets you zoom into the location.
As for the AR, it is as mentioned, a visual guide to make finding the item with greater ease.
Beyond that, the Plus version is everything the non-Plus version is. This kind of explains the US$10 (at US$39.99) premium over the standard variety when it becomes available starting April 16.