OnePlus has announced that it's moving away from its own Android-based Hydrogen OS in favour of Oppo's ColorOS user interface in mainland China. 

In the announcement, OnePlus described it as a customised version of ColorOS, suggesting that it won't be exactly the same as the software running on Oppo's latest phones. 

It's a move that will further raise the topic of just how independent these two companies are, and exactly where that line is between them. 

The two - along with Realme - are part of the same larger company, but all three are run as seperate brands, even though they all often use very similar technology and hardware. 

For instance, the fast charging and battery hardware is almost always the same, offering market-leading refuelling speeds. 

It's in the design and software department they've differentiated from each other in recent years. Even there, however, there have been similarities. 

Realme, for instance, used to run ColorOS the same as Oppo before switching to Realme UI, which in itself is essentially just the same as ColorOS but with a tweaked interface. 

The good news for anyone outside China is that OnePlus will continue to ship phones running Oxygen OS, which was recently redesigned to give it a fresh visual identity. 

OnePlus 9 series phones across the globe will continue to run OxygenOS, but in China those devices will run a tweaked version of the Oppo software instead.