The private costs are those such as raw materials, labour and other factors of production involved in the production process i.e those borne by the individuals and firms. These costs are covered by the prices at which goods are sold. IN theory, the price mechanism determines this price without taking into account social costs eg. the unintended or side effects of the production process such as depletion of resources cause by logging rain forests i.e those borne by society as a whole.
So in your example, the private costs would be those that are incurred in the process of logging the trees e.g. machinery, labour, transport of logs whatever. The social costs would be those such as the depletion of resources , the damage to local habitats and the pollution caused by the machinery used. yadayada....
