For starters as I said the story is different from the beginning with some plot points the same.
Seems Cosmo is kinda like mutant power so Seiya awaken it for acccident. Even so it requires training for common use.
The plot of the orphans of Kiddo is dropped at the most aside of Seiya.
The rebellion of Saga is different. Here in fact the Sanctuary know that Saori is Athena, but a dark prophecy of somewhere says that Athena will lose in the next battle with Hades and Poseidon and the humanity would be fucked so they decided "fuck Athena we the Saints win ourselves". If the prophecy is true or not is still to be know but for Aiolos sacrifice is probably Saga fucking.
When Seiya wins the Pegasus Cloth the Pope (Saga?) basically say him "don't use the cloth for personal gain or we'll be in your ass. This is specially important as the Galaxian Wars are a undeground tournament in a bunker in the middle of some dessert instead of fucking stupidly televised.
Due to the number of episodes to working the Galaxian Wars are super short: no hugging battle, here Gekki is one-shotted for Seiya.
Hyoga is more like his manga self where he is send by the Sanctuary to kill Saori and the rest but Saori basically convinces him that she is right. Here seems Hyoga orbit between the Edgy and the conceited one of the group.
The Seiya vs Shiryu battle is BY NO MEANS as good as the original and is impossible to make something of the same caliber in this age. Is good even so, with all and the weakness of the Dragon and the revive punch.
Dohko isn't purple.
Shun/Shawn is a girl yeah. Shawn is cute, aside of that there isn't really notable changes in her personality, aside that maybe she is not SO reluctant to fight until shit hit the fan.
For example if my memory works I remember the original anime Galaxian Wars as:
Jabu: Common faggot I'm gonna punch you.
Shun: Dude, I seriously don't want to fight you. I'm going to hurt you and feels bad. But if I don't have another option...
while here is:
Shawn: Dude, give up I don't like to fight.
Jabu: Come on bitch I'm gonna beat you.
Shawn: Men, I tried. you ask for it.
Without the plot of the Foundation Kiddo, here Shawn was simply bullied and Ikki taugh her to make a defensive fight because she doesn't like to fight.
This is important, the female Saints with mask plot point is dropped. Shaina uses a kind of tribal make-up maybe for the lulz and the only one with mask is Marin maybe because here she actually is Seika so is only for mistery.
I mentioned that Shawn is cute?
The enemy of the first part is a evil general that was friend of Mitsumasa Kiddo and was there when Aoilos die and give baby Athena and the Gold Cloth to kiddo, he took an arm of the Saggitarius Gold Cloth. He want to prove that the humans can win against the gods without Athena help and try to kill Saori using military and tech (he probably doesn't know he can't do jackshit against a massive flood or a evil eclipse but who can?).
The current Bronze Saints power is downgrade to the point that actually struggle against the military. Maybe the difference in ranks are a big gap in here as it seems for the flashback of Ikki where Shaka appears and seems pretty godly.
The story of Ikki training is basically the same. On the other hand Esmeralda is actually a blonde Shawn so with the current situation is...weird.
Oh, by the way this throws a bit of light in Guilthy as Esmeralda says that he wasn't always a piece of shit and one day someone appeared and after that he wore the mask and become like that. I always though that Guilthy was a waste of a interesting character.
This flashback is seem because unwittingly comically Ikki throws Genmma Ken and Hyoga reflect it with ice without even try it.
The Black Saints are a creation of the general using as a base the arm of the Gold Cloth kinda like the Steel Saints but this is actually Techno Magic.
Cassius is a Black Saint and Seiya and him basically end in a draw. The rest pretty much are overwhelmed by the Black Saints until Shawn figures his weakness. A damn clearly visible device instaled in the napes. Not evil counterpart of the Bronzes, but Cassius can use Black Meteors but without poison. Not Black Dragon damn.
Ikki is defeat almost the same as the anime/manga.
This first 6 episodes end with the appearance of Misty so I hoping for more.
OP is pretty good even if irkme a bit Pegasus Destiny. Maybe they couldn't pay for it?
ED is freaking awesome.