iOS 10.1 beta 5 is unexpected, considering that beta 4 was released only yesterday. And while yesterday's OTA was only around 30MB, today's build 14B72c comes in at around a whopping 1.95GB.
But today's iOS build is exclusive to the iPhone 7 and 7 Plus, so it probably contains the same connectivity fixes that we saw yesterday in iOS 10.0.3, which was also only available for those two devices. Even for an update that has those fixes, this one is pretty big. The release notes don't say anything about what's new.
It's also completely unsurprising that the macOS 10.12.1 Sierra beta 5 notes say absolutely nothing about the build. The build number is 16B2553a and it comes in at about 1.25GB.
The big new feature in both updates is Portrait Mode in the iPhone 7 Plus, and support for it in Photos. There are also improvements in Messages.