From The TimeSplitters Wiki

Both Generics are decorative items available in TS3's mapmaker. They cannot be moved or collected, and serve no purpose other than to make a level look less 'bland'. The exact nature of the item varies depending on the tileset it is placed in, but examples include an ornate heiroglyph panel in tomb or a large anti-tank barricade in military. The large generic object is, as its name suggests, the larger of the two.