I mean like all the stuff that displays in and around the code, that isn’t the code itself. For example warnings, hints, etc. An obvious example of something you can’t do in Neovim is display information in a smaller font. Generally speaking you just don’t have nearly as many options for creating information hierarchies in a UI consisting of ASCII characters.
In terms of turning things off, if you turn them off, then what’s the point of having the language server? (Not a rhetorical question - I would describe myself as a workaday programmer, not a master by any means.)