From Wikipedia:

“A utility bicycle is a bicycle designed for practical transportation, as opposed to bicycles which are primarily designed for recreation and competition, such as touring bicycles, racing bicycles, and mountain bicycles. The vast majority of bicycles that can be found in the developing world are utility bicycles. As such, utility bicycles are the most common form of bicycle globally.”

A Sport Utility Bicycle (SUB) rides like a sporty bike but also is capable of carrying heavy loads. A full cart of groceries, an eight foot ladder, a pile of 2×4’s, heavy work tools, another bicycle or whatever your cargo, a modern SUB can fill in where motor vehicles were needed in the past.