Dolphins jump higher,
Dolphins jump more often,
Dolphins have some more health,
Dolphins are tempted by multiple types of fish,
Dolphins interact with different sea plants,
Dolphins have an interactive inventory,
Dolphins are tame able,
Dolphins can do some tricks(Function pack needed),
Dolphins are much more active,
The player can interact with the dolphins in multiple ways,
Dolphins could make different kind of animated jumps,
Dolphins while hunt for fish at some times,
Some behaviors explained:
Dolphins interact with different sea plants and hunt for fish and pickup items. Some items they pickup inspire them to make those custom jumps, by adding a certain tag to them. The function pack detect when the dolphins jump and detects items around them and checks for player interaction.
Some more tips:
You can do a belly rub like animation by being close to the dolphin, then quickly look around 70 grades down.
And an Flukewalk like animation by quickly looking around 70 grades up.