You'd be surprised... XD Casshern Sins is so drastically different from Neo-Human Casshern that it might as well be a totally new independent series. I honestly don't know what they were thinking when they made Sins. In fact, if you changed the names of Casshern, Braiking Boss, and Luna, as well as giving Casshern a different suit, you'd have a different series right then and there. It disregards any and all continuity established in the original.
In Neo-Human, Casshern was a human who basically turned himself into a robot in order to defend humanity against the robotic forces. He was a superhero doing superheroic things. It was the typical good vs. evil thing. Luna was his love interest and partner who would fight the robots with him.
In Sins, Casshern is angsty, dark, and always depressed because of the fact that he caused the apocalypse and then forgot about it. Compared to Neo-Human, Sins has no plot and no bad guys. Luna became a death-hating goddess who basically came off as a jerk to everything and everyone.
To put it simply, they completely the utterly butchered the original series. I have nothing against Sins (you know, obviously XD) but the fact that it's supposed to be a reboot of Neo-Human makes me feel terrible for the fans of the show back in the 1970s. I mean, the way I see it, it's like taking the original Pokemon anime from 1998, redoing it in 2030, and changing it so where Ash was the head of a criminal organization that slaughtered Pokemon for the fun of it... or something.