Control mostly. Slave processes are controlled by the master totally and do work on the masters behalf. Parent/child does not work here as child processes are c

Control mostly. Slave processes are controlled by the master totally and do work on the masters behalf. Parent/child does not work here as child processes are created by the parent, and do not necessarily follow the parents commands. A child can do other work, without the parent being aware of the goals. Replicas on the other hand clone behavior, it has to be identical to the primary.