The palm nuts eaten by Hyacinth Macaws are larger and have 1, 2, 3 or 4 elongate meaty parts per casing.
The Licuri Palm Nuts eaten by the Lear's Macaw have smaller casings but contain one large meaty part.
It seems that the Lear's gets more "bang for the nut" than the much larger Hyacinth. They also opened and consumed the meat much faster than Hyacinths.