>a simple but important difference
Well, if you want to get technical linguistically, returning nothing is equally accurate to not returning anything. Anything is defined as "Something or someone of importance". So not returning anything makes sense as void is an incomplete type and thus not something of importance. Nothing is defined as "One that has no substance or importance; a nonentity", which is strikingly close to the definition of void as an incomplete type.
>(which is a fun past time btw)
That it is...
