PLA (Polylactic Acid) is one of the two most commonly used desktop 3D printing materials. It can be treat as the "standard" material as it is both odourless and low-warp. Moreover, PLA is made from corn-starch, making it more eco-friendly to use. Beside 3D printing, PLA is often used in food containers.
Compare to PLA, PLA HS is more durable and can withstand higher temperatures. Normal PLA can only withstand about 60 degrees but PLA HS can hold up to 90 degrees. In general, it is a higher quality PLA, with less moisture absorption, less shrinkage during printing and most important of all, its flexural strength is 50% higher than PLA, making it less likely to break. However PLA HS is rather expensive compare to normal PLA.
Woodfill is a wood-like material that gives printed objects a look and feel of fibreboard. Woodfill is made from wood particles and some polymer binders, making it meltable and extrudable for 3D printing. Currently WoodFill printouts are being use to mimic wooden items.
Flex filament as the way we call it, is a flexible material that feels like flexible rubber. It can be used to make bendable parts and joints, as well as items that requires a bit of starching. In terms of 3D printing, Flex doesn't require a heated bed.