Twi’ek’s have a widely varied representation in Star Wars; eyebrows are one of the facial features that seem to vary a little. Pretty much all female Twi’lek’s have human-like hair eyebrows, Oola, Aayla, the purple Twi’lek singer Lyn Me, Hera, Numa and more all have this feature.
Males on the other hand seem to have large and heavy brow that protrude out from the forehead. Bib Fortuna has one of the largest brows seen in Twi’leks. Cham Syndulla and other male Twi’lek’s seen throughout Star Wars Rebels and The Clone Wars also seem to share this heavy bulbous brow. And also do not appear to have hair on their brows.
The shapes of Twi’lek teeth tend to follow to veins, female Twi’leks tend to have flat human-like teeth. Aayla Securra, Hera, Oola and others all have these kings of teeth.
Male Twi’lek’s tend to have pointed teeth, like Bib Fortuna and Cham Syndulla, however, a little Twi’lek boy from the Clone Wars has flat teeth. It seems that male Twi’lek’s may vary between pointed and flat teeth.
Images from Cap-That.Com