Walmart just proved it has a huge advantage over Amazon

Walmart is throwing its weight around.

The largest retailer in the US is leveraging its substantial store footprint to make inroads against its online competitors.

Its plan to become an "omnichannel" comes into clear focus with the new Mobile Express Return initiative, which blends the online and offline into one seamless experience for the customer. Customers using the service can skip the regular customer service line to return items bought online.

As Walmart seeks to leverage its enormous network of stores as it becomes a bigger player online by launching two-day free shipping and pickup services, the distinction between ecommerce and brick-and-mortar falls away. The customer is just interacting with one brand: Walmart.

With the more than 4,700 Walmart stores in the US, no other chain in America can come close. That means 90% of the US population lives within 10 miles of a Walmart store, and Walmart is likely hoping customers who prefer to return items easily in store will choose the retail chain instead of online-only competitors.

Walmart isn't the only one diversifying its strategy. Top online competitor Amazon especially is making large bets in the physical world, including drastically increasing its distribution center footprint across the US.

The most notable of Amazon's new initiatives is its $13.7 billion acquisition of Whole Foods. In comparison with Walmart, Whole Foods has only 400 stores, however. It will take quite a while before its store number can rival Walmart's if that is its goal. Walmart is proving it can move online faster than its online competitors can move offline, and the largest retailer in the US is #1 for a reason.

Amazon seems to understand this. Department store Kohl's also recently announced a small partnership with Amazon to accept returns in some Kohl's stores, and another purchase in the vein of Whole Foods isn't out of the question.

For now, though, Walmart remains king of the physical world.