It's like comparing a wool sweater to an acrylic one.
Wool is the most durable.
It is heirloom quality.
It is tighly woven, thicker and has less fuzz than other felts.
But it is also much more expensive. (like 10x more than acrylic)
As you can see here.
100% wool on the left, 80/20 wool felt blend, acrylic on right
The fibers are most tightly woven in the wool felt and you can actually see the darker table showing through on the acrylic felt.
But there are times that I can not use 100% wool because the colors are limited and it can be a little thick for cutting super fine details...thats when a wool/rayon blend comes in handy. It still has the durability of wool, but it usually comes in more colors, is less thick and easier to find.
Acrylic felt has its place too, don't get me wrong.
This felt is great for crafting. This is what we use with the girls to create fun things.
I usually use it when I am trying new felt designs and don't want to burn through the more expensive wool felts.
Acrylic felt can be readily found at any craft store and even at your local Wal-Marts.
It's cheap (like 29 cents/sheet) and great for use on kid crafts. Some acrylic brands are even made using recycled soda bottles. (so that's good too)
But this, people, is why I prefer to stick to 100% wool for my hair accessory needs.
It's the quality, the durability and the soft, less fuzzy texture that stands the test of time.