The changelog for both handsets are same which can find below:
- Added OnePlus Laboratory for OnePlus 6
- Optimizations for screenshot function
- Support for quick reply in landscape mode – now easier to reply to new messages when watching videos
- Gaming mode enhancement
- Now supports world clock with weather information
Both the OnePlus 6 and 6T are the 2018 flagship phones, but the 6T is the successor to the OnePlus 6 with some new features. The OP 6T is also the first is the first phone from the company to feature an in-display fingerprint sensor.