The most obvious difference is their size. A llama is quite a bit larger, at around 290-450 pounds, while an alpaca is downright dainty at 110-190 pounds. Llamas also have coarser wool coats, while alpaca fiber is longer, finer, and very soft. (Hence, tons of alpaca sweaters and mittens, while llama sweaters aren't exactly taking the world by storm). Both are domesticated camelids, a group of herbivorous mammals that also includes camels, vicunas, and guanacos.