All X are not Y.
and
Not all X are Y.
The first statement, taken literally, says that no member of group X has attribute Y.
Most people don't mean it that way, but by using that construct, they sow confusion.
If you mean that only some members of group X have attribute Y, while some do, then say that:
Not all X are Y.
If you mean that zero members of group X have attribute Y, then please use a different construct:
No X are Y.
