That is PET polyester carpet. It is like olefin, in that it does not hold stains. However, it crushes and mats almost immediately and due to abrasion of the fibers, looks dull and dingy even after thorough cleaning. One sure way of identifying it is that the wand pushes on it like it was on ice or glass. It has a different feel when cleaning than nylon or olefin. It is a cheap carpet, often touted for being made from recycled products, but it's crap and has a lifespan of next to nothing in high traffic areas. Clean similar to olefin.
Take care,
Lisa