Refined oil extraction uses high heat and chemical solvents, both of which damage the bio-active compounds responsible for the benefits of the oil. The yield in refined oil is higher. To make refined oil appear attractive, it is processed to remove gums (a thick layer that forms in the oil) and then refine it further with acetic acid, hexane or bleaching soda. Sometimes they also do double-refining process. When external heat of around 200 celsius is applied it destroys all the nutrients.
Cold-pressed oil is the oil extracted in its natural form. Oilseeds are just pressed (crushed) to yield out the oil. The method is just pressing, nothing else. Cold pressed oil in its natural form is very healthy with all-natural nutrients and flavour. Cold pressing is more expensive as it takes longer time and produces lower yields – but it is the safest, most natural extraction method.