Extra means premium, it has the lowest amount of free acidity and peroxide of all the olive oils. Virgin means it’s the First Cold Press. Whole fresh olives crushed to release the oil. Cold is under 86°F. EVOO has been mechanically pressed, and the oil separated from the pomace (the pits, flesh and juice).
Anything that does not meet the free acidity and peroxide values cannot be labeled Extra. Any oil produced using solvents or heat cannot be labeled Virgin.
Detailed info here http://www.oliveoiltimes.com/extra-virgin-olive-oil