In case any of you were wondering, here's what I pulled up on google. Taken from soldiercity.com.
100% cotton ripstop:
Lightweight, breathable, wind resistant, and durable. The ripstop reinforcement provides a checkered pattern to resist rips and tears. Ideal for warm to hot climates. May shrink more than the other materials.
Polyester/cotton twill:
The preferred cloth for most civilians. Ideal for all weather conditions. Slightly less breathable than 100% cotton in the summer but provides better protection in the winter.
Polyester/cotton ripstop:
The cloth of choice for federal agencies. Durable, colorfast, resists fading, tearing and abrasions. Resists wrinkles and shrinking. All climate - breathable in summer, wind resistant in winter. Offers the ultimate in long lasting performance and will outlast all other BDU materials.
Nylon/cotton twill:
Proven to be long lasting and sturdy from decades of military use. Best for temperate weather.
Does anyone prefer one material over another, and if so, why? Thanks.