Right, we do mean something different with "the UTF-8 doesn't matter". I interpret that as the only difference between the internal representation of the strings is whether the UTF-8 flag is set or not -- but you use it to mean "it doesn't matter whether the internal encoding is UTF-8 or not". 
use Devel::Peek;

my $x = my $y = "\xC9ric";

utf8::upgrade($x);
utf8::upgrade($y); utf8::encode($y);

Dump($x);
Dump($y);

# Now $x and $y differ only in the setting of the UTF-8 flag

say substr($x, 0, 1) eq substr($y, 0, 1) ? "equal" : "different";

__END__
SV = PV(0x8cd80cc) at 0x8cea9ec
  REFCNT = 1
  FLAGS = (PADMY,POK,pPOK,UTF8)
  PV = 0x8cef6e8 "\303\211ric"\0 [UTF8 "\x{c9}ric"]
  CUR = 5
  LEN = 9
SV = PV(0x8cd803c) at 0x8ceaa28
  REFCNT = 1
  FLAGS = (PADMY,POK,pPOK)
  PV = 0x8cf38b8 "\303\211ric"\0
  CUR = 5
  LEN = 9
different

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In reply to Re^3: Jargon relating to Perl strings by JavaFan
in thread Jargon relating to Perl strings by ikegami

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