$, == $OUTPUT_FIELD_SEPARATOR 
The output field separator for the print operator. If defined, this value
is printed between each of print's arguments. Default is undef.
(Mnemonic: what is printed when there is a "," in your print statement.)

$\ == $OUTPUT_RECORD_SEPARATOR
The output record separator for the print operator. If defined, this value 
is printed after the last of print's arguments. Default is undef.
(Mnemonic: you set $\  instead of adding "\n" at the end of the print.
Also, it's just like $/ , but it's what you get "back" from Perl.)

$/ == $INPUT_RECORD_SEPARATOR
... [zu viel Text zum Kopieren, bitte nachschlagen;
     kurz: Default ist ein Zeilenumbruch enthalten]