Subject: axle question

Howdies,
I installed new bearings and seals in both wheels today, 2 spacers up
front, none in rear worked well. Both axles are same length and diameter
but the non-threaded ends are slightly different, one being 1/2" longer
than the other. I'm sure it will become apparent when I assemble (a ways
off yet) but anyone remember which axle is which? Trying to sort things
out in advance.
Ray