Authorial voice is what characterizes a particular person's writing overall. Frex, mine tends to use rich description and wide vocabulary, unless I have a reason not to do that in a certain story. Other writers excel at different things -- some are known for writing stories heavy in dialog, for instance.
Character voice is what distinguishes an individual person in a story. A young character will have simpler speech and knowledge than an older character. Prejudices and expectations also color word choices. A character's interests or expertise will affect what they notice, and thus, what they talk about or describe and how they do that.
Between the two are regional clusters of varying sizes. If you look at all the stuff I write in my main fantasy setting of Hallelaine, or my dark fantasy setting of Penumbra, or ellenmillion's shared world setting of Torn World, then you can see how each of those has an overall flavor. Penumbra, for instance, has very stark writing almost devoid of description -- a departure from my usual mode. Then if you look closer, characters from the same area sound somewhat alike. In Torn World, there's a certain worldview and vocabulary shared by the Northerners contrasted with that shared by the Southerners. So my Northerners sound more like each other than like the Southerners, and vice versa; but together they are Torn World folks who have things in common with each other, as contrasted with my characters from some other world.
Authorial range varies too. I have an exceptionally wide range when it comes to writing about different people and places, in different voices and tones. Some of my characters are almost nothing like each other or myself. There are writers with wider ranges -- such as Harlan Ellison -- but not a lot. Most people specialize more. Some writers also have a unique voice that, while it manifests differently in their diverse settings, can be recognized as theirs even beyond the usual authorial choice issues. An icon of this phenomenon is Joss Whedon. Compare what his characters say in Buffy the Vampire Slayer and Firefly vs. what Joss says in interviews. He has an incredibly strong vocal stamp whose underlying patterns manifest in wildly different details across his different settings.
What have you noticed about these things?