Easier to use
Much more secure (all communications use end-to-end encryption)
Higher quality connections
Free even for commercial use
Google Duo only supports calls with up to 12 participants (although that is enough for most uses other than online classes or seminars)
You can read more in an article by Taylor Kerns in the Android Police website at: https://bit.ly/30rpICV.
Google Duo for Windows, Macintosh, Chromebooks, Linux, and other operating systems may be launched at: https://duo.google.com. Even better, specialized apps for Google Duo use on Android devices or on iPhones/iPads/iPod touch devices may be found in the respective app stores for those systems.