One day after Microsoft announced its holiday-season sales milestone for the Xbox One, Sony did so for its PlayStation 4. And as you might expect, given its additional time in the market and wider availability, the PlayStation 4 has come out on top, selling 4.2 million units through the end of 2013.

Microsoft announced Monday that it had sold more than 3 million Xbox One consoles through the end of 2013.

"The momentum of the PlayStation 4 system keeps getting stronger, and we couldn't be more thrilled," Sony Computer Entertainment President and Group CEO Andrew House said. "After a remarkable launch, we look forward to bringing even more exciting content and continuing to explore the power of the PlayStation 4 system by adding new features and services, including PlayStation Now, in 2014."

Although simple math puts the PlayStation 4 ahead, Microsoft has a few factors going for it that put its Xbox One sales numbers in perspective. The PlayStation 4 launched a week earlier than did the Xbox One, and was available for 6 weeks in 2013 compared with 5 weeks for the Xbox One. The Xbox One is $100 more expensive than the PlayStation 4. And the PlayStation 4 is available in far more markets—53 in total—than the Xbox One, which is available in only 13 markets.

As I noted in yesterday's story about the Xbox One sales milestone, 2014 should be a pivotal year for both consoles and will play a bigger role in their overall successes than did this past holiday sales season. Both firms are betting big on exclusive game titles, and Sony's PlayStation Now, which will provide cross-platform access to games on consoles and gaming titles, could prove to be an interesting differentiator. Microsoft has pinned its hopes on a broader, more entertainment-driven strategy that will likely prove more popular with a mass audience, however.

Regardless, both the Xbox One and PlayStation 4 are off to strong starts, and have sold in far bigger numbers at launch than did the companies' previous consoles.

Related: "Is Sony Edging Ahead of Microsoft in Next-Gen Console War?"