~~~
'First var
'Flag var
:echo&length (s-s) dup [ s:length n:put tab ] [ s:put ] bi ;

:get-first (s-s) dup #0 s:fetch !First ;
:reset TRUE !Flag ;
:check-string (s-s) dup [ @First eq? @Flag and !Flag ] s:for-each ;
:same? (s-sf) reset get-first check-string @Flag ;

:show-instance over 'at_%n_'%c_differs\n\t s:format s:put ;
:differences
  tab #0 swap [ dup @First eq? &drop &show-instance choose n:inc ] s:for-each nl drop ;

:yes drop tab 'identical s:put nl ;

:test (s-) s:keep echo&length nl same? &yes &differences choose ;

s:empty    test
'___       test
'2         test
'333       test
'.55       test
'tttTTT    test
'4444_444k test
~~~