These bushes need more cold hours during winter in order to produce blueberries than bushes in the other two groupings.
There are (as of 2007) over 50 known varieties in the Highbush group. In fact, they’re actually grouped into two sub-groups: Northern Highbush (Vaccinium corymbosum and Vaccinium australe) and Southern Highbush.
Highbush are the most common varieties of blueberries found being sold fresh in supermarkets — they’re the variety of blueberries that have the frosted look to them.
The bushes tend to produce the largest blueberries out of the three groupings.