Quick answer
A control cable carries signals and switching commands rather than bulk power — between control panels, switchgear, relays and instruments in power stations and substations. The conductors are small (typically 1.5 or 2.5 sq mm) but numerous: APAR's XLPE control cables run from 2 up to 61 cores in a single cable at 600/1000 V, each routine-tested at 4 kV. A power cable is the opposite: few cores, large cross-sections. See control cables up to 61 core.