It's likely PS4 was outselling XB one at least 2:1 for a short time on Amazon. It's lucky this is a slow time of year and 2:1 doesn't represent as big of a numerical gap as it would at different times of year.
“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
"When the power of love overcomes the love of power, the world will know peace."
Jimi Hendrix