http://www.perlmonks.org?node_id=588680


in reply to Re^2: Use of single quotes versus double quotes
in thread Use of single quotes versus double quotes

There is no runtime difference unless there is a variable being interpolated, in which case only double quotes are appropriate. The perl parser treats them the same otherwise:
perl -MO=Deparse -e ' $a = "foo"; $b = ''foo''; $c = q{foo}' $a = 'foo'; $b = 'foo'; $c = 'foo';
perl -MO=Deparse -e ' $a = "$foo"; $b = q{$foo};' $a = "$foo"; $b = '$foo';