Just days after Walmart made a splash by announcing its Amazon Prime competitor, Amazon used yesterday’s earnings announcement to share a new Prime milestone: more than 50 million items, up 73 percent since 2015.

Walmart’s new free two-day shipping program covers only 2 million products — a fraction of Prime’s inventory.

In Amazon’s earnings release, founder and CEO Jeff Bezos also revealed that “tens of millions of new paid members” joined Prime in 2016. Amazon has never shared a total member count, but late last year analysts estimated the number at 65 million just in the US.

As tempting as it is to compare Walmart’s new offering to Amazon Prime, the reality is that free two-day shipping is pretty much where the comparison ends. Prime members get a number of additional benefits that have helped generate customer loyalty, such as free streaming music and video, free book borrowing from the Kindle Store, early access to certain sales and more. Those digital benefits are popular, too. Amazon said yesterday that Prime members more than doubled their video, music and reading activities in 2016.