New York (CNN Business) Walmart and Target are taking different approaches to adding robots in stores, a split that will have an impact on the companies' massive workforces and shape the future of automation in retail.

Walmart WMT Both of these legacy brick-and-mortar companies are testing robots in their warehouses., the country's largest retailer and private employer, expects to add self-driving robots that scrub floors to 1,860 of its more-than 4,700 US stores by February. It will also add robots that scan shelf inventory at 350 stores and bots at 1,700 stores that automatically scan boxes as they come off delivery trucks and sort them by department onto conveyer belts.

Walmart's 178,000-square-foot supercenters are expensive to operate, especially as more shoppers shift online. The company is adding robots to help it increase worker productivity and control costs. Walmart has around one million hourly workers in its stores.

The company says "smart assistants" will reduce the amount of time workers spend on "repeatable, predictable and manual" tasks in stores, allowing workers to switch to selling merchandise to shoppers and other customer service roles.

With the robots, Walmart will reduce the hours it assigns workers to unloading boxes and mopping the floors in some stores. That will lead to some employee attrition over time, the company says.

The "Auto-S," Walmart's shelf-scanning robot, moves around aisles and identifies which items are low or out of stock.