Lists contains items of different types, that can be presented in very different ways.

Above the grid, we can display a way to select between different visualization modes, and a way to restrict items displayed to one specific type. In both cases, the user may select just one of the possible choices.

The second row may only be visible for some values of the first choice.

The number of items available for each type may be displayed next to the name of the item type.

In the bottom design, instead of a choice of visualization modes, the first row is a first level of type of item. Not sure if it’s a good idea to use the same design.

The second row is not simply a special filter, in the sense that object of different types may not be displayed in the same list. Different columns may be presented depending on the type selected, as well as different actions below the grid.