If I'm not mistaken, seems like 1:1 to me. Maybe this writer did the VN translation? Either way, will definitely read, thanks.
Take it as rumor as I haven't read much into it, but from what I've read in various search results there was supposedly someone translating the VN, and quit when they found out that the novel was already translated (since it's more or less the same). Some time later, someone from Russia took the English translation for the Novel and applied it to the game. Not so much that it's the same person, but that the text was copy-pasted over in that case.
Edit: Having read the translator's blog, it seems that he was translating the version posted for free on their website. As mentioned it appears that a heavy amount of content in the novel is illustrations, but it also appears that Case03 is exclusive to the novel, hence why it's not translated. He mentions in the comments feeling obliged to finish what he'd started (and feels he'll end up buying the books) but gives no promises as he's moved on to a new project.
So, for a quick rundown:
(Translated) Visual Novel: Case01.
(Translated) Web Text-Only Version: Case01 and Case02.
Book Version: Case01, Case02 (Translated) and Case03 (Untranslated).
And the second book which came out recently (Untranslated). Not sure what Raven Notes is but supposedly it's an addition for the book which was added to the web version, but judging by its length I'm sure it's not Case03.
There's always the possibility that the physical copy might have differences in the story (probably not, though), and if the translator ever finds a copy, we might end up seeing Case03 and/or the second book translated. He only finished Raven Notes a month ago so who knows.
