Trophies are back with the PlayStation 4, but they wont be the same as the PlayStation 3 trophies. The system will remember each trophy you earn , but will also classify them based on their rarity. The trophies will be designated bronze, silver gold and platinum depending on how difficult it is to obtain them. Sounds similar so far.
However, the rarity isn’t determined beforehand. The rarity of any given Trophy is dynamic and is calculated across the whole PlayStation user base. A Trophy will be determined difficult based on how many people actually have earned it. Rarity can and most likely will change over time.
Trophies will still fill a progress bar that gradually levels up your profile and still have to sync online. They can be earned offline and later synced. The PS4 Trophy interface will list all Trophies a player has earned across the Playtation 3, PlayStation 4 and PlayStation Vita.