There is a type of peace which is merely an absence of war. People do not necessarily get along, nor care for each other. However, as long as one does not bother the other, all is well. This is contrasted to a vastly different type of peace. It is a true peace, where people care for each other.
Sheep are a perfect example of the former type of peace.
One sheep does not necessarily care for the others in the flock. As long as any specific sheep gets its food to eat, it will not bother any other sheep. Sheep co-exist with each other. The brothers of Yosef, on the other hand, demonstrated the latter type of peace. They lived together in a unit, caring for each other's needs, concerned for each other's welfare.