This is full of spoilers!
My first post about the differences between the original Yamato TV series and the remake Yamato 2199 remains my most popular post (that doesn’t use StumbleUpon). I’ve wanted to write a more in-depth post since then, but I lack the time. One day, though.
But let’s not leave you hanging! A thread on reddit’s /r/anime asked this very question. The original poster wanted someone to enlighten them on the changes. As that series is, for some unknown reason, not talked about a lot, I immediately jumped to the challenge. Here’s the post. Stuff in brackets  are edits/notes I made to the original post.
> I have not watched the original series but I heard that some things were changed. Does anyone care to fill me in on what the differences are?
Oh god YES there are. Lots of them. It’s still very similar, but in my honest opinion one reason why Yamato 2199 is such a good series is that every change they made improved the series. I do a quick episode-by-episode rundown on the differences for the first 22 episodes on my blog, but the tl;dr of it is that Yamato 2199 speeds up the plot and then fills in the holes with new and (more) interesting content. Here are some key areas, some of which have great implications:
- More races/planets. In the original, the amount of habitable planets could be counted on one hand: Iscandar (which was a dying planet actually), Gamilon, Earth, and the one with bee people [Beeland]. The Gamilons want Earth because their planet is dying, but they and humans cannot live in the same environment. Gamilons need a heavily irradiated ecosystem, which humans obviously cannot live on. In terms of races, they was the humans (who only lived on Earth), the Iscadarians (only a couple of them), the bee people, and the Gamilons. No subraces. [A better term might be “subjugated races”]
- Rei is not present in the original series. THEY HANDLED THIS SO WELL BY THE WAY. She is the sister of Yamamoto, who was a pilot in the original series. In Yamato 2199, they changed a lot of the genders of the crew because the original sorely lacked female characters (the only one was Yuki). So, not only did they gender flip a character, they created an entire back story for it! That is, Yamamoto the male pilot from the original, was killed in 2199 and replaced by his sister, Rei. Oh my god so meta. I love it.
- Yuki is a LOT more tomboyish in 2199. She was so ladylike and in the romance with Kodai was more like a housewife. A supportive role. I like Yuki in 2199 a lot more.
- Balan got a pretty cool change. It was originally a rocky planet with an artificial star orbiting it (not sure how that works). In 2199 it was changed into an artificial gas giant with an artificial star in the center. In the original, Domel wanted to crash the Yamato into the artificial star, but the Yamato shot it with the Wave Motion Cannon (we still get this scene in the original, but earlier). I think I might be wrong, though.
- The bee people. Holy shit I am so glad they changed this. Remember that extinct species they found in the middle of the series? You know, when they’re getting chased by that monster thing in the forest? Well, that planet is populated by a race of bee people… in the original, they made honey for the Gamilus. I don’t remember why but there was this big rebellion and everything. I thought it was silly honestly.
- Melda Ditz was a man and a side character. He only had one episode, and he got killed when he was released. Melda Ditz obviously was not killed, but they gave her more importance in the story.
- GATLANTIS! You don’t know who that is, do you? Remember when Domel was fighting “barbarians” on the out edges of their territory? Those green ships? Those guys are actually the villains of the second season (and the breakthrough movie that made the series so popular, Farewell to Space Battleship Yamato). You see, the cool thing about Gatlantis is that they disguise their invasion fleets as comets (they’ve also called The Comet Empire). They’ve conquered galaxies, and they’ve made it to the Large Magellanic Cloud… possible villains in the Yamato 2199 movie?!
- Analyzer was given his own episode, and a mighty fine episode at that. He was more of a comic-relief character.
- The psychics. Not in the original.
- The Imperial Guard (blue ships). Not in the original.
- That whole assassination/conspiracy thing didn’t happen. So, Norio Wakamoto is not in the original. 😦
- AND POSSIBLY THE GREATEST AND MOST SIGNIFICANT CHANGE OF THEM ALL… THE SURVIVAL OF THE GAMILONS! In the original series, they’re wiped out. Killed off. Every single one of them, except for Lord Desslok (or Dessler) and a few of his men (actually they get killed, too, although not in the first season). Yup. The Yamato actually commits genocide in the original; they shoot a volcano with the Wave Motion Cannon that sets off all of the volcanoes on the planet, which then kills everyone on the planet.
Those are the ones off the top of my head.
There’s probably more! Hopefully I can do something more in-depth (or do a “Yamato 2199 versus Warhammer 40,000” post… Nah). Stay tuned!