Spain is the world's largest olive oil producer, Italy is second. But production volume and quality are different concepts.
Italy stands out for its enormous diversity of cultivars (over 500 varieties) and strongly regional character. Spanish production is more concentrated, dominated by Picual, Hojiblanca and Arbequina varieties.
Both countries produce excellent olive oil. Italy's advantage is diversity and terroir expressiveness, Spain's strength is scale and consistent quality at a more affordable price.