The fact is that when both consoles were announced, they were referring to FP32 TFlops throughput... because nothing was known to be differently at the time. Sony completely marketed the Pro as a 4.2TF performance machine.. and will continue to do so.
As I said, they will use words like 'effectively' to describe that the console can punch higher than that if developers utilize mixed precision computations in their games.
They aren't going to market the Pro as an 8.4TFlop machine.. because it can never realistically hit that throughput in any modern game. Additionally, MS is simply not going to release a console one year later that is less powerful than the Pro.. when the entire mandate is to design the most powerful console upon release...
You can question it until they are made to confirm it.. but you know it in your heart to be true lol..