It's... complicated. I'm not the one to get into too much detail, but briefly...

There were console adaptations, most notably by the now-defunct company Alchemist. These included a bunch of enhancements, such as redrawn character art and backgrounds, event CGs, voice acting (by the anime cast), and new music. The mods from 07th-Mod[07th-mod.com] are based on these (specifically, the PS3 versions). There's more information behind the "install" button at that site. There were also console-exclusive arcs.

07th Mod provides this handy chart[07th-mod.com] for how the arcs relate.

Also, were there any changes from the original novels in the steam version? I imagined they changed the music, but I heard they censored some Satoko sprites and also that some lines were changed (I don't know if it was in this version).

And also, on a semi unrelated note, do I have to read umineko before watching gou?

引用自 Joaco：

Also, were there any changes from the original novels in the steam version? I imagined they changed the music

They also redrew the sprites. But then again, so did Alchemist. The original versions have the author's own character art, which is rather rough. (He clearly wasn't trained in it, although it has gotten better over the years.) So, there tends to be a desire to replace it with something more polished.

but I heard they censored some Satoko sprites

Yeah, originally in "Tatarigoroshi-hen" (the third arc), in the part where Keiichi finds her in the bath, she eventually loses the towel (I think it's when she falls on the bridge) and ends up naked. To my knowledge, in Japanese culture this isn't too big a deal, since it's a child and is not sexualized. But needless to say, a lot of people weren't okay with those sprites, so they were removed and replaced with the ones where she's still wearing the towel. It wasn't just for the Steam version, though. MangaGamer did the same thing for their earlier release (the one using the BGI/Ethornell engine; the Japanese original uses NScripter), and as far as I can tell, so did Alchemist's ports.

and also that some lines were changed (I don't know if it was in this version).

It was in the Alchemist ports. Just the few little bits with dirty jokes were censored, and trademark references were altered (e.g. the Japanese nickname for the statues of Colonel Sanders, "Kenta-kun", from "Kentucky Fried Chicken", was changed to "Randy-kun").

And also, on a semi unrelated note, do I have to read umineko before watching gou?

Can't answer that one, sorry.

I see, thanks.

引用自 Joaco：

I see, thanks.

Oh BTW, MangaGamer originally did replace the music (personally, I don't like what they came up with, as they reduced the number of tracks, and the ones they did make lacked subtlety, including making some tense scenes way too intense). But for the Steam version, they used the original. Interestingly enough, though, 07th Expansion itself issued some new music for Higurashi a few years back, which the Steam version took in.