Smell will not help to identify thier sex. It could be one is just developing faster or it could be slightly different phenos when growing from seeds.

You could plant 10 seeds and find one plant grows a little taller then others, or one might have more fragerence then others....and maybe 1 in 10 will be more potent then others.

Growing regular plants, you would be looking for that one great plant that gives you everything you are looking for and then make that your mother plant to make cuts/clones from. But alas, autoflower's don't really give you that option.
OM