Hellmann's and Best Foods are brand names that are used for the same line of mayonnaise and other food products. The Hellmann's brand is sold in the United States east of the Rocky Mountains, and also in Latin America, Europe, Middle East and Canada. The Best Foods brand is sold in the United States west of the Rockies.
Hellmann's and Best Foods are basically marketed the same way. They both have similar logos and web sites, and they have the same English slogan: "Bring out the best." The Spanish slogan is "Haz una cara...Hellmann's!" (roughly translated to "Make a Hellman's face!"). In Brazil it is "Hellmann's, a verdadeira maionese" (Hellmann's, the true mayonnaise).
Both brands were previously sold by the U.S.-based Best Foods Corporation, which also sold several other food products in addition to Hellmann's and Best Foods mayonnaise, before it was acquired by Unilever in the 1990s. In 2006, the container size was decreased from 32 ounces to 30 ounces, with no accompanying decrease in price.