Fleece is a soft and fuzzy fabric that's made from man-made materials like polyester. It feels like wool but isn't as heavy or scratchy. People use it to make all sorts of things like clothes, blankets, and even furniture covers.
Polar fleece is a special kind of fleece that's made from a specific type of polyester. It's thicker and warmer than regular fleece, and people use it to make things like jackets, hats, and cozy blankets for when it's really cold outside. It's also good at wicking away sweat, which is why athletes like to wear it when they exercise outside.