The difference between the Ricardian model of trade and the immobile factor model is that: O Ricardo assumed one factor of production while the immobile factor model assumed two factors of production, labor and capital. O Ricardo considered the countryâ s workforce as an endogenous variable, while the immobile factor model considered labor supply as exogenous. O Ricardo assumed a barter economy while the immobile factor model introduced money into the system. O Ricardo assumed labor was immobile between industries, while the immobile factor model considered labor to be immobile only between countries. O Ricardo assumed labor employed in each sector to be endogenous, but the immobile factor model assumed labor employed in each sector to be exogenous.