How does Walmart compete with Amazon?

Walmart's sales are three times those of Amazon, but lacks many of Amazon's technological capabilities.  To catch up, it is investing (losing money) to acquire the data necessary to train an AI shopping system:

Walmart is using Jetblack’s army of human agents to train an artificial intelligence system that could someday power an automated personal-shopping service, preparing Walmart for a time when the search bar disappears and more shopping is done through voice-activated devices, said Jetblack CEO Jenny Fleiss.

In addition,

Walmart bought India’s biggest e-commerce site. It has been buying up small online retailers including men’s apparel company Bonobos and is testing autonomous cargo vans for home grocery delivery in places such as Surprise, Ariz.