Amazon built a big business with tiny orders. Now Walmart is stealing the strategy.

• Amazon's typical shopper makes 72 purchases per year from the site, usually with small basket sizes.
• Now, Walmart's CFO says Walmart+ members are increasingly placing orders of just one or two items.
• The Walmart US CEO also said it takes a shopper four orders on average to embrace frequent delivery.

Amazon was able to achieve e-commerce dominance in part through millions and millions of tiny orders.

The typical Amazon shopper makes 72 purchases per year from the site, according to consumer analytics firm Numerator, spending about $37 per order for an annual total of $2,662.

By contrast, Walmart's typical shopper shops a little less frequently and spends more per transaction, and tends to shop more in-store.

But now, Walmart's CFO John David Rainey says Walmart+ members — who spend twice as much as the retailer's typical customer — are starting to act a little more like Amazon shoppers.

"Maybe this is intuitive, but they tend to shop more frequently and also have smaller baskets. They're using us for those one or two items," he said Wednesday at the Evercore ISI Consumer & Retail Conference.

Rainey also said that while Walmart's e-commerce orders historically tilted toward pickup, more shoppers are opting for delivery in recent months.

"I believe that that's a trend that's not going to reverse," he said. "It really speaks to how customers are thinking about this convenience factor for us."

In addition, as America's grocery king, the company is able to glean compelling insights into shopper behavior, Walmart US CEO John Furner said Tuesday during the Oppenheimer e-commerce conference.

"When you look at our baskets by type of channel people shop, and we can see differences," he said. "When you see the ingredients selling, it tells you the intent."

In other words, knowing what's going on with customers' shopping baskets gives a good clue into what's going on in their minds.

Furner also said it takes a shopper four orders on average to embrace delivery.

"After the fourth delivery, we see the patterns change: more usage, more frequently," he said.