The Magsafe connector, and your Magsafe 2 as well, can be plugged in either way without any difference, totally reversible.
Looking at the connector - pins 1 and 5 are ground (earth, I suppose); pins 2 and 4 are V+; and the tiny center pin is a data/control line, that controls the LED color, and power output of the charger.
The output is DC, not AC, so would not use the L and N identification, AFAIK.
pinout diagram here:
http://en.wikipedia.org/wiki/MagSafe#Pinout