transporting materials through a plant is a kind of function
transport_of_mail is conveying_materials. cargo_ship is material_transporter. electricity is useful_way_to_transport_energy. transport_of_people is conveying_materials. electricity is not useful_way_to_transport_energy. smuggling is conveying_materials. material_transporter is transportation_device. moving_earth is not conveying_materials. transport is diffusion. moving_earth is conveying_materials.