The United States is not a member of the International Olive Council (IOC). Therefore, the IOC retail grades of have no legal significance in the U.S. However, in 2010 the USDA established Standards for Grades of Olive Oil which closely parallel the IOC standards.
Here’s a summary
U.S. Extra Virgin Olive Oil
This oil is the most sought after for its delightfully fruity flavor and aroma. It must not exceed a free fatty acid
content of 0.8 g per 100 g, or 8%.
U.S. Virgin Olive Oil
Not as fruity as Extra Virgin, it still offers and pleasant flavor and aroma. It must not exceed a free fatty acid content of 0.2 g per 100 g, or 2%.
U.S. Virgin Olive Oil Unfit for Human Consumption Without Further Processing
This is a mechanically extracted oil of inferior flavor and aroma. It is equivalent to the IOC’s “lampante” grade.
U.S. Olive Oil
A blend of both virgin and refined oils, it has very little flavor and aroma.
U.S. Refined Olive Oil
This is made from refined oils with some restrictions in its processing.
The terms “light” or “extra light” refers to olive oils that are processed with heat and chemicals to remove impurities. Light olive oil is sometimes blended with other oils as well. You’ll find their flavor to be less prominent that extra virgin oil.