What is the difference between a llama and an alpaca?

When Andy learned that Jude wanted a llama for his birthday, he suggested that Jude and I google the difference between a llama and an alpaca.  Jude and I read about the differences and I had a strong preference in favor of the smaller, cuter, curly haired alpacas.  Jude had a strong preference for the larger, longer haired and uglier llamas.  Then Jude went to Andy and said, “You shouldn’t have asked that question.  Mom and I got into a big fight about it.  She wants an alpaca and I want a llama.”