"I'm not sure what the reason is for the discrepancy with EA's estimates.
It could be it excludes Pro/One X numbers.
It could be that EA excludes a territory like Japan (they used to do this last generation)
It could be that EA estimates PS4 at a lower number. (Which would be weird given Sony release the official numbers)
It could be that installed base =/= sell through in EA's eyes. So replacement consoles sold wouldn't count and only people actively using consoles would count?
EA's estimates aren't wrong. I'm just fairly certain one of the above things is true.
Ultimately what we do know is PS4 sell through was 73.6m at the end of 2017. Xbox One is less than half of that total which shows the big gap between the two in terms of sales. But that's something that has been known for a long time."
^ this could be a explaination right?
If we ignore PS4 + XBO sales in japan, do the numbers EA supplied make sense?
Yep, assuming they left out Japan sales for PS4 that would the estimates up to 108-109 million (5.8 million Japan sales).
So, 108 million - 73.6 million = 34.4 million (give or take a few 100k since these are estimates), which sounds much more like the sales for Xbox One as of December 31st 2017.