The Brushed & Oiled finish is achieved by 'brushing' the face of the planks during production to remove the slightly softer parts of the oak surface.
This, especially after oiling, enhances the beautiful texture of oak and underlines the wooden look of the floor. It also protects the surface better and makes it more resistant, as scratches and marks don't show up as much as on a smooth finishing.
Oak being oak, there will be a variance in the depth of texture, depending on the grain of each board. Some boards may be quite smooth with not much texture but others may be quite 'rough' where more of the softer fibers of the face have been brushed out.