For instance, Jar Jar has eyes that protrude from his head..... while Boss Nass has eyes normally in his head.
Im convinced Boss Nass isnt a Gungan, he just showed up one day in Otoh gunga and demanded to be elected leader of the Gungans and the Gungans didnt know what how to respond so they all panicked and made Boss Nass their leader.
I think Boss Nass has a special design to make him stand out from the rest of the Gungans just like how Poggle has a special design to stick out from the rest of the Geonosisians.
It is like how humans' appearances can vary greatly, I just figured Nass is simply from a different racial group of Gungans, plus he seems to be obese.
Maybe it's all the weight Boss Nass packed on... but yeah, I assume it's so he stands out among all the Gungans who are generally the same size
Boss Nass's appearance used to bug me too... until I realized those were his ears tucked behind his headpiece. Then it all made sense. He's just a fat gungan with his ears pulled back. No issues with it now. Love the character design, actually.
Why do humans vary so widely? Some are 6 and a half feet tall, muscular, good looking. Others are 4ft tall, fat, and uhh... not good loooking...
That is very common in fiction and even in real life to have leaders or commanders look different. Vader's TIE is a different shape so you can tell his apart from the other TIEs, Cody has different armor so you can tell him apart, etc. Doctor Who uses this alot too with Cyberman commanders having black head handles, cone heads, or clear domes showing off their brains. Dalek leaders tend to be different colors from the drones, or have extra stuff on their casings like the supreme Daleks.
Seems to be pretty consistent: Boss Nass is just obese, like Orn Free Taa, with the respective physical consequences.
Because it doesn't matter if you ARE a giant bipedal frog thing with rabbit ears... the sheer Brian Blessedness just overwhelmed the computer programming.
Oddly enough his first name is Boss. That's not a title. Just kidding. I think there is a tradition in adventure sci-fi fantasy of alien or mythical races having leaders who stand out from the rest of the group. Poggle the Lesser looks different from other Geonosians. Look at the Goblin King in the Hobbit. Even the Queen Alien in Aliens. I like it actually.
Rugor Nass is an Ankura Gungan and Jar Jar Binks is an Otolla Gungan. We saw more Otollas because ILM was mostly mass replicating Jar Jar's character model, with minor changes like see with Captain Tarpels.