Monster Hunter Freedom is the PSP version of Monster Hunter G with extra features, such as new colored bosses and a Felyne kitchen. Monster Hunter Freedom is the Westernized name, while Monster Hunter Portable is used in Japan. Both games are essentially the same.
The Subspecies of monsters act differently than their normal counterparts. Most move faster when in rage or have changed the attack patterns (like using more of the attack that the normal one use the least.) Kokoto village has changed a little due to the addition to the farm and the cherry blossoms.