This is great info. Thank you for all the input! From what I can gather from all this discussion is:
Fluffy is cover that isn't dense. Meaning, cover that gives the predator, LMB, room to move, hover , stalk etc... something for him/her to snuggle up,against or related to while they are in there wait and attack mode, or rest mode.

There probably needs to be some context to why I asked the question in the first place: I am getting ready to build a new pond from scratch. When I look at all the cover options out there, it is easy to see what a dense cover/prey fish hiding place would look like. But, when I see some of these so called "fluffy cover" options, some of them don't look like they would hold much fish. Example, a 6 ft pvc tree with 1 inch pieces of pvc randomly sticking out. They have very little real cover to them, very little shade etc.... Yet, they supposedly hold fish. There are many commercial options out there. Whether it is a mossback Trophy tree or a porcupine fish tractor, it's just hard for me to visualize why a bass would want to hang out by a small 1" pvc branch spaced several feet apart? I can visualize why a bass might hang out by a large tree with descent size branches all around, with some room to move, or tires randomly piled up so,there are plenty of places to hide, with shade, yet room to maneuver. Just trying to figure out what materials to use to make my "fish city" in several areas of my pond?