Suspended ceilings - pertain to an additional ceiling installed beneath the primary structural ceiling of a room or space. Also known as drop ceilings, false ceilings, or suspended grid ceilings, they consist of a suspended grid system with ceiling tiles or panels.

On the other hand, ceiling structures encompass the various elements constituting the ceiling of a building or room. This includes primary structural components like beams and joists, as well as supplementary features such as lighting fixtures, ventilation systems, and, in the case of suspended ceilings, the grid and tiles.

To sum up, suspended ceilings specifically denote a type of secondary ceiling installation, while ceiling structures encompass all components and features related to the ceiling of a space.