Packaging and marketing aside, generally speaking, women's scents tend to be lighter, sweeter, and are frequently found in the floral or oriental families. Men's scents tend to be strong, rich, woody, earthy, leatherish, herbaceous, and aromatic. Of course, other factors come into play in the universe of eau de what-have-you, like personal preference and the way a scent develops on the skin.
Speaking of the way a scent develops on the skin, it does make sense then that gendered fragrances tend to mimic the natural body odor or chemistry of a man or a woman. And as far as unisex scents go, fresh, citrusy scents tend to reign supreme in that category. Of course, there are all sorts of clichés and stereotypes in regards to male and female scents, but for you, what makes a fragrance masculine or feminine?