The OnePlus 5 is the hot new OnePlus-branded smartphones, but the OnePlus 3 and the OnePlus 3T are still very powerful smartphones, and they'll both get Android O before the end of this year. OnePlus actually confirmed this during an AMA (Ask Me Anything) on Reddit recently, the company assured its consumers that the update will land to the two 2016 flagship smartphones before this year comes to an end, which was the case with Android Nougat update for the OnePlus 3 and the OnePlus 3T last year actually, both phones received the update at the very end of the year.
This confirmation is reassuring considering that Android O did not launch just yet, Google did release several Developer Preview builds of Android O, and this version of Android is expected to land in the near future, it might even arrive before Google's second-gen Pixel devices. In any case, this update will refine the experience on both the OnePlus 3 and the OnePlus 3T to an extent, as both devices are running OxygenOS, which is essentially stock Android with a ton of useful features on top of it. This means that you will basically get all the features that Android O brings to the table, unless they're exclusive to Pixel phones, of course. Improved battery life will be included, while you will also get the picture-in-picture mode, which will allow you to watch a YouTube video in a small, customizable window while you're doing something else on your device, for example. In addition to that, Android O will also bring more improvements to the notification shade, it will give you even more functionality in that regard, and so on.
The OnePlus 3 and the OnePlus 3T are actually quite similar, these two phones look identical on the outside, and they share most of the specs as well. The OnePlus 3T comes with a larger battery, though, and it also sports a more powerful Snapdragon 821 64-bit quad-core SoC. The OnePlus 3T comes with a sapphire lens on its rear-facing camera, while the OnePlus 3T also comes with a 16-megapixel camera, compared to OnePlus 3's 8-megapixel snapper. All in all, these two phones are quite similar, but the OnePlus 3T is the most powerful handset here. OnePlus will probably release a more specific timeframe for the Android O update later this year, so stay tuned.