Are you having trouble keeping track of all of the different messaging apps that Google offers? Don't feel bad; a lot of us do. In fact, it feels like Google has a number of redundancies in this space, and with its latest move, we get the feeling that the consolidation has begun.
Take Allo, for example, which is set to take the place of Hangouts in the official "Google Mobile Services" package going forward. That means that vendors won't need to bundle Hangouts with their devices, although they still have the option to should they want to offer a more complete package. Even if they don't, however, you would still be able to download it from the Play Store, which isn't a grand inconvenience.
So what is Duo? Given the fact that Google wants it to replace Hangouts, you might imagine that it's a similar messaging app - but it's not. Not even close. Duo targets the likes of FaceTime in emphasizing video conferencing. The app has no messaging capabilities; you simply choose a contact, and shoot them a video call.
What makes this all the more interesting is that Google also has Allo, and it combined with Duo would become an actual Hangouts replacement. Allo is similar to Facebook's Messenger, putting a huge focus on emojis. It's all very confusing, isn't it? "Duo" can give the impression that both video and text are supported, but that's not the case. Instead, it's named as such because it's in the context of two people conversing.
Perhaps an even more confusing thing? Allo isn't being made default like Duo is, even though the two apps go hand-in-hand. It's truly baffling, and is probably something that will change in the future.
Given that Duo is going to be such a major focus for Google, if video calling is your thing, go ahead and give the app a test drive.