Closed tread describes a stairs with a full timber riser between each tread (the part you step on). With this option it is not possible to see through the stairs (see Photograph A & B).
Open tread allows you to see through the gap between each of the treads and can help to brighten up a hallway if necessary. In order to meet Building Regulations it is necessary to use a small timber riser (Photograph C) or a stainless steel bar (Photograph D & E) to ensure that the gap between each tread is not too big.
Photograph C Open Tread Small Timber Riser - Closed String
