Set Type controls whether Pointwise creates structured or unstructured domains and blocks. Structured and unstructured grids can both be included in the same grid to create a hybrid grid. Note the type only applies to domains and blocks. At the connector level, there is no difference between structured and unstructured grids.
To create structured grids, select Structured. Any domains created when Structured is selected will be structured quadrilateral surface grids. Any blocks created when Structured is selected will be structured hexahedral volume grids.
To create unstructured grids, select Unstructured. Any domains created when Unstructured is selected will contain triangular surface elements. Blocks created when Unstructured is selected may contain tetrahedral, pyramidal, and prismatic elements depending on the particular grid generation method used.