Resistance to Bee Stings
Nylon material is tougher and more resistant to bee stings than cotton/polyester blends. Neither suit is completely impervious to bee stings, however. Nylon is simply more difficult for bees to penetrate with their stingers.
Climate
Suits made of cotton/polyester allow for more airflow and are more breathable. Nylon suits trap moisture and are less comfortable to wear in hotter climates. But keep in mind that bees are also more likely to sting someone perspiring or covered with excessive moisture, which may increase the amount of strikes received while wearing the nylon suit and may increase the likeliness of the wearer getting stung.
Color
Beyond the material it's made from, a suit's color also largely determines its effectiveness. Bees are more likely to sting darker colors, so suits that are light in color are ideal.