Xb one reached 2 million on 9 December, after 18 days on sale in all markets. PS4 reached 2 million on 30 November after 16 days on sale in North America and 3 days on sale everywhere else.
Comparability-wise you could look at "market days" (my made up term) on sale: Xb one sold for 18 days in 13(?) markets = 234 market days. PS4 sold for 16 days in 2 markets and 3 days in 36 markets = 108+32 = 140 market days. So PS4 took 96 fewer market days to reach 2 million consoles sold.
Of course not all market days are equal so you'd have to introduce a market size coefficient to refine those numbers. But I think you'd still find that PS4 has sold significantly faster than Xb one.
“The fundamental cause of the trouble is that in the modern world the stupid are cocksure while the intelligent are full of doubt.” - Bertrand Russell
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