Q:

Not one vs None

I have two sentences:

He is not one of us.
He is none of us.

While I can clearly understand the first one, does the second one make sense and is it correct?
What is difference here between "not one" and "none"?

A:

The first one makes sense insofar as it means that "He is not a member of our group."  The second one does not make sense in the context of the former statement even though "none" comes from Old English and is a per se contraction of "not one".  I would not ever say, "He is none of us" to mean that he is not part of our group; I would use "He is none of us" to tell the person that there is not one person here who is the individual that he is looking for.  Despite this oddity, most of the time, "not one" and "none" can be used interchangeably.  Could one possibly interpret "He is not one of us" and "He is none of us" as equivalent?  Yes, one probably could; however, it would cause a lot of confusion.  So, to clarify for you, SovereignSun, here is how I, as a native speaker, would interpret the two statements:

"He is not one of us." (He is not in our group.)
"He is none of us." (The person whom you are looking for is not here.)

A:

The meanings are
A. not any member of our group (i.e. no person among those in our group)
{not one} {of us}

We are, none of us, perfect.  
We are, not one of us, perfect.
There is, none of us, but has some flaw in his character. 
There is, not one of us, but has some flaw in his character.

B.  not a member of our group (i.e. does not belong to our group)
{not}  {one of us}

He is from another (country, tribe, group, clan, county, ... whatever). He's not one of us.

In the 18th c. and earlier, "none of us" could be used to mean "not one of us", not a member of our group, and the usage has survived in regional dialects.

A stranger, he is. He's none of us.

