Eine komplette Gleichsetzung beider Zeichen (kanonische Äquivalenz) ist aus Gründen der Kompatibilität (eineindeutige Zuordnung der in ISO 8859-1 enthaltenen Zeichen) nicht möglich. Siehe: The Unicode Consortium: The Unicode Standard, Version 14.0 – Core Specification, Kap4, S.159.
„The Unicode Standard [...] has to strike a balance between uniformity of treatment for similar characters and compatibility with existing practice for characters inherited from legacy encodings. Because of this [...] some pairs of characters might have been treated as canonical equivalents but are left unequivalent for compatibility with legacy differences. This situation pertains to U+00B5 µ micro sign and U+03BC μ greek small letter mu [...]“
The Unicode Consortium: The Unicode Standard, Version 14.0 – Core Specification, Kap7.2, S.308. „For compatibility purposes, a few Greek letters are separately encoded as symbols in other character blocks. Examples include U+00B5 μ micro sign in the Latin-1 Supplement character block and U+2126 Ω ohm sign in the Letterlike Symbols character block. The ohm sign is canonically equivalent to the capital omega, and normalization would remove any distinction. Its use is therefore discouraged in favor of capital omega. The same equivalence does not exist between micro sign and mu, and use of either character as a micro sign is common.“
