>>723609778
Every Chapter has had some significant differences depending on your choices. Even in Chapter 1, going out of your way to spare everyone changes the ending.
It's also missing the point to argue that "small" changes don't really matter in the big picture. There are a hundred different ways to play Undertale that all lead to "the same ending."
>Deltarune's version of the genocide route only results in minor story changes.
The changes in the Weird Route are not "minor," but even if they were we're only halfway through the story and it's been very clearly signaled that things are going to go off the rails in Chapter 5. There's not really any "major" changes in Undertale Genocide up until you fight Undyne and get into Hotland.