Both articles mention the 38 million number, I suspect that is the number of people ordered to evacuate their home while the number who have actually evacuated the area is the three million number.

I've worked emergency communications and 911 dispatch during wildfires and a surprising amount of people don't leave their homes during an evacuation order.

I mean, it's still an impressive number of people... but yeah a lot less than 38M:

So far, floods have affected 37.89 million people in 27 provinces, autonomous regions and municipalities. As many as 141 people are dead or missing, and 28,000 houses have collapsed.

A total of 2.246 million emergency evacuations have been made, according to Zheng Guoguang, vice minister of emergency management