Monster Hunter Freedom is the first game in the Monster Hunter Portable/Freedom series for the PSP, content-wise, it is based on Monster Hunter G, including many of its features, but it is not a direct port of the game.
Many features from Monster Hunter G were retained, along with the introduction of new features.
Monster Subspecies from MHG, unlike later games, subspecies aren't announced in the Quest menu, the only way to know what species of a monster will be in a quest is if the Quest Description specifically states color.
Monster length is registered, but only for the largest size.
Number-based Armor Skill system, like in MHG.
All Areas from the First Generation.
Treasure Hunt quests.
Training School is now accessed from the Village.
Sharpness levels from MHG.
Gameplay modified to suit a framerate of 30 frames per second, with weapon responsiveness taking a severe hit that would be corrected in later Portable/Freedom games.
Kokoto has some aesthetic differences, for example, the bushes now have pink leaves and the building behind the Village Chief is now accessible, which is known as the Guild Hall, where players can join hunts together much like Dundorma and Minegarde Town, on a smaller scale.
Being the first game in the Portable/Freedom series, gameplay is rough and not a perfect replica of that in Monster Hunter G, players coming from other games may have issues adapting.