There are three different concepts here:
Carriage Return (CR, Retorno de Carro) -> This supposedly moves the carriage to the left edge. In ASCII (ISO-646 IIRC) it corresponds to character 0x0d (hexadecimal for decimal 13).
Line Feed (LF, Avance de Línea) -> This supposedly advances the "page" one line, without returning the carriage to the left edge. In ASCII, it corresponds to character 0x0a (decimal 10).
New Line (NL, Nueva Línea) -> This is an abstract concept for the added effect of CR+LF. It corresponds to the C language '\n'.
Now, different operating systems have different conventions for the meaning of the above three. Basically:
Unix: NL=LF (so a single LF has both effects).
MS/PC-DOS, Windows: NL=CR+LF (you need both chars for both effects).
Mac: NL=CR (a single CR has both effects).
I hope I haven't confused you further.