Added a note in each regarding the fact that unicode strings that look the same

may not compare equal (due to the possibility of multiple representations).

Doc/library/unicodedata.rst

@@ -107,7 +107,7 @@ the following functions:
    based on the definition of canonical equivalence and compatibility equivalence.
    In Unicode, several characters can be expressed in various way. For example, the
    character U+00C7 (LATIN CAPITAL LETTER C WITH CEDILLA) can also be expressed as
-   the sequence U+0043 (LATIN CAPITAL LETTER C) U+0327 (COMBINING CEDILLA).
+   the sequence U+0327 (COMBINING CEDILLA) U+0043 (LATIN CAPITAL LETTER C).
 
    For each character, there are two normal forms: normal form C and normal form D.
    Normal form D (NFD) is also known as canonical decomposition, and translates
@@ -126,6 +126,10 @@ the following functions:
    (NFKC) first applies the compatibility decomposition, followed by the canonical
    composition.
 
+   Even if two unicode strings are normalized and look the same to
+   a human reader, if one has combining characters and the other
+   doesn't, they may not compare equal.
+
    .. versionadded:: 2.3
 
 In addition, the module exposes the following constant:

Doc/reference/expressions.rst

@@ -1040,7 +1040,7 @@ Comparison of objects of the same type depends on the type:
 
 * Strings are compared lexicographically using the numeric equivalents (the
   result of the built-in function :func:`ord`) of their characters.  Unicode and
-  8-bit strings are fully interoperable in this behavior.
+  8-bit strings are fully interoperable in this behavior. [#]_
 
 * Tuples and lists are compared lexicographically using comparison of
   corresponding elements.  This means that to compare equal, each element must
@@ -1328,6 +1328,12 @@ groups from right to left).
    cases, Python returns the latter result, in order to preserve that
    ``divmod(x,y)[0] * y + x % y`` be very close to ``x``.
 
+.. [#] While comparisons between unicode strings make sense at the byte
+   level, they may be counter-intuitive to users. For example, the
+   strings ``u"\u00C7"`` and ``u"\u0327\u0043"`` compare differently,
+   even though they both represent the same unicode character (LATIN
+   CAPTITAL LETTER C WITH CEDILLA).
+
 .. [#] The implementation computes this efficiently, without constructing lists or
    sorting.