what are the three shape differences in the cranium between the two species? (look specifically at the frontal, temporal and occipital bones.)

Facial deflection, Relative palatal length, Relative snout length.

Explanation:

In some species that are very close, that they have the same genus even a different specie, biologist have develop a system in which the craneal characteristics can be measure.

For example, in the species Macaca fascicularis and Macaca fuscata, there are some studies in which the bones where measure to observe if they belong to the same specie or not.

As a conclusion of the comparison of this geometric morphometrics one specie has longer bones than the other, so they do not belong to the same specie. Also this kind of method it is used to compare fossils with living taxa.

Hope this info is useful.