Normally it means the card has additional benefits over and above normal credit cards and gold cards and requires you to have a higher credit rating than for the basic or gold card. In practice given the wide variation in offers and credit requirements by different brands it really is relative to the other cards being offered by the same brand.

Usually offered to people with higher incomes and a good credit history. This card has a minimum credit limit of $5,000 and may include member benefits.

Similar to the Gold Card but with a higher credit limit. Normally requires a higher level of income.