The bilberry is native to central and northern Europe, and grows wild in rocky, hilly areas. The bilberry bush is notoriously difficult to cultivate, and the majority of commercially available bilberries are picked by hand, making them more expensive than blueberries. Blueberries are primarily native to North America, although some species have been introduced to parts of Europe. Blueberries are easy to cultivate, and while they can grow in most parts of the continent, the bulk of the blueberries harvested in North America come from Maine and Canada.
The major difference between bilberry and blueberry bushes involves the way the berries cluster. In bilberry bushes, the berries grow individually, and occasionally in pairs. In contrast, blueberries form in large clusters. If you see blue-colored berries growing in the wild, check the clustering to tell what kind of berries they are.
While they may be hard to tell apart alone, it's easy to distinguish a bilberry from a blueberry when you can make a direct comparison. Bilberries are typically smaller than blueberries, and darker in color. When cut open, bilberry pulp is purple to blue in color, whereas blueberry pulp is usually a light green. Blueberries tend to have more juice than bilberries, as well as a more noticeable "crown" on the end not connected to the bush.
Bilberries and blueberries are both known for having positive effects on human health. Blueberries are well known for being high in antioxidants and anthocyanins. However, wild bilberries typically contain the same compounds at much higher levels -- up to four times higher. According to HealWithFood.org, eating blueberries or bilberries regularly can be a good way to keep your skin healthy, prevent acne and even reduce the risk of varicose veins.