In its quarterly earnings report today, Microsoft announced that it shipped 3.9 million units of the Xbox One to retailers worldwide from its launch in late November through the end of 2013.

It's important to note that shipments to retailers aren't the same as final sales to end consumers. Though those numbers usually track relatively closely (since retailers order new shipments to replenish stocks of systems they've actually sold), many of those 3.9 million shipments in 2013 might be sitting on retail shelves for a little while in 2014. Still, the new report gives a bit more context to Microsoft's previous announcement that it had sold "over 3 million" Xbox One units through to consumers by the end of the year.

Sony, for its part, announced earlier in the month that it had sold 4.2 million PlayStation 4 systems through to consumers by December 28 of last year, showing a slight advantage over Microsoft. With supply constraints becoming less of a factor for both companies following the end of the busy holiday season, we'll soon see if either system is able to show a significant market advantage through sustained consumer demand in 2014.

Microsoft also announced that it had shipped a relatively healthy 3.5 million units of the long-in-the-tooth Xbox 360 to retailers worldwide in the last quarter of 2013. That's down from 5.9 million Xbox 360 shipments in the same quarter the year before. Still, those kind of continued, late-in-the-generation sales, combined with life-to-date shipments of over 80 million units worldwide before the 2013 holiday season, suggest the aging Xbox 360 will continue to see significant support from developers and publishers at least through 2014. That might be especially true in the US, where the Xbox 360 sold nearly 1.72 million units during holiday quarter, according to previous reports from industry tracker NPD.

The strength of Xbox hardware and software sales helped contribute to a 68 percent increase in revenues for new Devices & Consumer Hardware division, which encompasses Xbox hardware sales, third-party game sales, Xbox Live subscriptions, and Microsoft surface tablet sales. That division saw a 46 percent decrease in gross profits however. Meanwhile, Microsoft saw sales of first-party games fall 58 percent year-over-year in the quarter, a decrease it attributed to the lack of a major Halo release in the 2013 holiday season.