600D is a plain weave polyester material that has a pvc backing. This material is waterproof due to its pvc backing, however it is not UV treated and will perish in the sun over time.
Saila is a 100% solution dyed polyester ripstop base fabric that it is then laminated to a soft non-woven polyester backing. This material has an additional Teflon treatment for water repellent finish. This material is waterproof.