As the busiest retail weekend of the year begins late Thursday night, the differences between how affluent and more ordinary Americans shop in the uncertain economy will be on unusually vivid display.

Budget-minded shoppers will be racing for bargains at ever-earlier hours while the rich mostly will not be bothering to leave home.

Toys “R” Us, Wal-Mart, Macy’s, Kohl’s, Best Buy and Target will start their Black Friday sales earlier than ever — at 9 and 10 p.m. in some instances — with dirt-cheap offers intended to secure their customers’ limited dollars. A half a day later, on Friday morning, higher-end stores like Neiman Marcus, Saks Fifth Avenue and Nordstrom will open with only a sprinkling of special sales.

The low-end and midrange retailers are risking low margins as they cut prices to attract shoppers, while executives at luxury stores say that they are actually able to sell more at full price than in recent boom years.