There are two major differentiators: moisture content and appearance.
Grade A vanilla beans are often referred to as ‘gourmet’ or ‘prime’ vanilla beans. They are dark and pliable with 25% – 35% moisture content, which allows the flavor and aroma to seep into food and beverages quickly.
Grade B or ‘extraction grade’ vanilla beans only have about 20% moisture content. Since they are too dry to scrape the caviar out, they are mainly mixed with other ingredients to make vanilla extract.