Econ 101 tells you supply and demand determines the price. We know the supply for both. So any difference in resale price is entirely due to demand.
Below is a chart of PS4 and Xbox One console prices before and after launch.
Both consoles are selling for prices higher than their retail prices (PS4 $399 and Xbox One $499). Playstation 4 prices have been relatively stable in the $580-600 range. Xbox One prices dropped $50 on launch day from $700 to $650.
PS4 and Xbox One have different retail prices so adjusting the chart to show the premium people are paying helps to see the relative demand between the two.
Playstation 4 consoles have been reselling for 150% of retail price. Xbox One was selling for 140% of retail prior to launch but prices then dropped to 130%.
Prior to launch people expected Xbox One to be harder to find then it actually was on launch day.
Any sale before launch day is based on the expectation of supply, but not the actual supply. To really compare demand between Xbox One and PS4 we need to look at prices after launch because at that point supply was the same.
The chart above shows the premium customers were paying for the two consoles with the launch days aligned and the premium paid 1, 2, 3, etc days after launch.
Since launch, consumers have been paying a higher premium for Playstation 4 consoles than Xbox One consoles. With supply being constant at 1 million units each, demand is higher for Playstation 4.
This indicates that when supply becomes readily available for both consoles Playstation 4 will sell more units.