The cable tray is mainly used for laying power cables and control cables, and the busway is usually used for laying wires and communication cables.
Structurally, a bus duct is a sheet metal duct containing either aluminum or copper busbars (metallic strips or bars that conduct a substantial electrical current) in a grounded metal enclosure.
Cable bus is supplied with short circuit bracing, and conductors are phase arranged for system balance. Cable tray has no short circuit rating or system balance. The cables are protected due to the full rigid enclosure. However cable bus is free air rated, where wire in conduit generally needs to be de-rated.
Busbar uses less space than cable systems. This is a major advantage when dealing with thousands of amps. Cable requires large bend radii that take up a lot of space. The compact nature of the busbar also ensures that the tightly compressed conductors inside the busbar are isolated and reliable