"눈과 얼음은 무엇이 다릅니까?"
Translation:What is the difference between snow and ice?
That would be 눈과 얼음은 다릅니까? You should notice the missing word is "무엇이" which is "what." 눈과 얼음 receive 은 to the be topic, 무엇 receives 이 to be the subject, so another way of looking at it is thus: "In terms of snow and ice, what is different?" but no one would ask like that, hence the more natural English translation they've written.