What's the difference between yarn and wool?

Dear users, dear authors,
what is the difference between yarn and wool? 

Good question—I’m not exactly sure myself.
Well, I use thread for sewing, of course, and wool for knitting and crocheting. But when it comes to cotton, I sometimes call it cotton thread, and with acrylic, I tend to call it wool.

Wool is wool—the stuff that comes from sheep, alpacas, rabbits, etc.
Everything else is yarn.

That makes sense. But what about blends, like in sock yarn? Is it always wool as long as an animal was involved?

Well, as soon as it contains animal fibers, it’s wool. And if you’re not entirely sure whether it’s wool from an animal, do the burn test: if it smells like horn and curls up when it burns, it’s animal-based; if it smells like paper and behaves like paper, it’s cotton; if it smells like petroleum and clumps up, it’s acrylic.

Best regards, Inge

Strictly speaking (according to the EU Textile Labelling Regulation), only the fiber from a sheep’s fleece is considered wool. Therefore, the product must definitely contain spun sheep’s fleece. For fibers derived exclusively from other animals, the name of the animal must be specified (e.g., alpaca wool).
Everything else (e.g., acrylic) is technically yarn.
In everyday language, however, the distinction isn’t applied so strictly. When labeling materials, though, it’s important to be precise.