Going over the Macross Chronicle World Guide for the Meltrandi and the Glossary entries for Exsedol Folmo and Meltrandi it seems Zentrans and Meltrans different more than just genders.
Zentrans are products of genetic engineering and uses organic looking technology or organic technology.
Meltrans while genetically engineered are also cyborgs with bio-optic nerves and use inorganic looking technology.
The difference can also be seen in their ship designs.
Now on to augmentation. Exsedol's entry tells he used to look like his TV version but once he joined Macross 7 he looked green with a large head. This is apparently for brain storage capacity. This also resulted in him having tentacles. Now Grace on the other hand with Macross Galaxy went for the cybernetic enhancement augmentations while looking perfectly organic.
Two different strategies to body augmentation. Genetic engineering and cybernetics. But it seems the Protoculture went more advanced on the bio technology route. Golg Boddole Zer was more of a bio computer for his ship in DYRL. The Bird Human and Evil Series were organic weapon WMDs.