Link to Snow's claims?
As for the difficulty, the game doesn't punish you anymore for all kinds of mistakes:
Getting caught unprepared in a monster's roar would usually guarantee you getting bit or bum rushed. In P3 your recovery time is faster so you can escape, even if the monster was facing you when it did it's roar.
Monster damage isn't as punishing anymore. Gone are the days where you could only take 2 or 3 glancing hits before getting KOed.
Tighter hitboxes. You can easily escape more tail swipes, charges and other attacks because the ridiculously large hitboxes from the earlier iterations have been fixed. (I'm not arguing to bring them back though, this is just a natural consequence.)
Felyne comrades. One of their most useful behaviours now, is to knock you out of animations liked being windpressed or stunned. Again, helps avoid being punished.
Faster recovery time from falls. New animations let you bounce back up on your feet in no time. A lot of times, this opens up more windows of opportunity to attack, as you often recover right underneath or behind a monster.
Lower hitpoints all around. Monsters generally have lower life.
Stamina design. Stamina has been added to monsters, which limits and controls how much they can do in a period of time. It's geared to mixing up the gameplay, which is a good thing. The unintended sideffect though, is that monsters are no longer relentless in their attacks. There will be guaranteed downtime where you can land in some seriously damaging combos. No such thing existed in the older games.
Felyne drink skills. Some of these skills are too good. Like Retention, which preserves your HP and stamina even if you get KOed. Completely circumvents the need for an armor that boosts your HP.
Less aggressive minions. The smaller monsters will not chase you down as much. Bullfangos were a huge headache in the older versions, in P3, they will only engage you once you're within a certain distance.
Weapon abilities. All the weapons have now expanded movesets, allowing you to deal with more situations where you couldn't in the previous games.
Expanded farm operations. It's easier to procure materials more than ever. Giant BBQ grills, cat mining and quests, automated fishing and so forth.
edit: From Tri? My bad, reading comprehension fail. Still, all of the above is quite valid with regards to the series in general!
