The difference between this model and the previous ones is that the first does not assume comparative advantage as a law, but explains the concept (Salvatore, 2010). Indeed, the difference in the relative prices of raw materials before trade between countries is caused by the different relative abundance of factors and relative prices of factors, which turns into a difference in the absolute prices of factors and raw materials (ibid). The immediate cause of the trade is, therefore, due to the fact that the absolute price of raw materials differs in the two nations (ibid). Second, the HO model includes the factor price equalization theorem, which assumes that “international trade will lead to the equalization of homogeneous or identical factor returns across nations” (Salvatore, 2012, p.82). Thus, if international trade occurred, it would affect wages and homogeneous capital gains, which are expected to be the same in each trading nation.