So the biggest change is in Gamilas/Gammalons and Dessla/Desslok. We see the whole Gamilias society, including people who were conquered and serve the empire but as second-class citizens. There is one woman, a psychic, who is the last of her race. Fascinating character

Dessla is a real dick in this series. Nowhere near as casual as in the original. At the end, he's prepared to sacrifice millions of his people to stop the Yamato, and it's the Yamato that saves his people. When they have the ship gunfight at the end, there's none of that cocky comment about the earth's forces being led by "a little boy",the insult he threw at Wildstar. There's no redemption for him.

The Gamilas worship the Iscandarians as gods. They confuse Yuki for Yurisha (Starsha's sister) and kidnap her at one point. Dessla is also in love with Starsha but she rebuffs him.

There is much more contact with Gamilas, including exchanges of people. This leads them to realize they are no different except for skin color.

The show has more naval references. There is a "submarine" that can "submerge" into another dimension. It surfaces, shoots torpedeos, you name it. And the Gamilas keep talking about "sinking" the Yamato.

The Gamilas are much more obvious Nazis now. Generals have German sounding names and their collar logo looks like the SS lightning bolts.

The friendship and rivalry between Sanada and Kodai is severely toned down. In the original, it felt like Kodai was in charge once Okita went down. Not here. Sanada is in charge and has no friendship with Okita. There's also no reference to bionic/explosive limbs, either.

Starsha is pissed at the humans for creating the Wave Motion Gun. She tells them the Wave Motion Engine was for propulsion and defense. Earth made the gun on its own and she almost doesn't give them the Cosmo Cleaner.

Kodai's older brother survived the battle of Pluto and was taken prisoner but the ship crashed on Iscandar. Starsha could not help him. He records a final message to the ship and his brother. His ghost inhabits the Yamato on the journey back to earth.

The Cosmo Cleanser isn't a big machine. It's literally built into the body of the Yamato like a neural network. Pretty cool how it works.

Analyzer/IQ9 is nowhere near as bad as he was in the original. No sexual harrassing of Yuki. In one episode, he tries to reach out to an Gamilan android and it becomes a mash up of I, Robot, GitS and Blade Runner, but incredibly well done.