4D penguins are the fourth dimensional counterparts of penguins. They usually hold D-Stars instead of Power Stars and they give them only when people help with their problems, much like the penguins in the First Dimension. These Penguins have a slightly green tint on their beaks that can be easily distinguishable from the Penguins of the First Dimension.
Juveniles resemble smaller versions of their adult counterparts, but they act very much different. They act in a similar way to that of a immature toddler.