Virtually all the cream you buy in the supermarket has been ultrapasteurized, a heating process that extends the life of the product. Ultrapasteurized cream will keep for several weeks unopened. Some folks find this factor a convenience.
Plain pasteurized cream is fresher and more perishable. Use plain pasteurized cream for whipping, if you can get it; ultra takes a lot longer to whip. Small dairies and some organic sources sell the plain pasteurized. Whole Foods and Trader Joe’s carry it, too.