Nidin-Alfolken (Great Elves) are the tallest and often considered oldest of the Alf race. Like most other Alfolken, the Great Elves have a close affinity to both life and death magic and believe in preserving a keen balance between spirituality and the sciences. The great elves especially hold a deep interest in medicine and history as they believe those two fields best reflect the twinned gods Arbor and Codex. As their name implies, the Nidin-Alfolken reign over the heavily forested nation of Nidinis and seem to take presidency over many of the other elven off-shoots that reside there… With the exception of the violent, brutish Troff-Alfolken (Swamp Elves) and the miniscule, wary Seff-Alfolken (Sand Elves).
While all other Alfolken can trace their origins to the Nidin-Alfolken, the origin of the great elves themselves is a complete mystery,and the only rift between their twinned belief system is in fact their conflicting explanations of how they came to be. The religious half claim the gods put them there, while the more scientific believe they are an offshoot of another now extinct race of Alf.
… Which in turn is an offshoot of yet another extinct race of alf. Which in turn is an offshoo–

Great Elves are identified by their:
Horns –
 unique to Great Elves alone. Females grow larger, more complex horn shapes as they grow in age. 
Tall, slender, but muscular formsEspecially in their neck and abdominal region. Perhaps to help hold up their large horns.
Identum Coloured Skin, Hair and Eyes – Most other alfolken usually have their identum/Soul colour represented in just their hair or eyes.
Standing on the balls of their feet – Foss-Alfolken/River Elves are the only other offshoot to do this.
Long tails with tufted ends Seff-Alfolken/Sand Elves have tails as well, though they are entirely fluffy. … Chinchillelves.
Height – While Moss Elves are noticeably larger in comparison, the Great Elves can still reach an impressive height of 6.7-7.2 feet on average. … This might include their horns. They ain’t telling.

(The two Greater Elves in the image are Empress Celaul Ul’shar and her husband Arlan Ulshar when they were in their younger years. Bless’em!)