“La Reine des neiges” does mean “Snow Queen”. In French, you would not say “La Reine de neige” or “La Reine de la Neige” because it does not necessary sound right. In this case, I do not know exactly why it is plural in French and not in English. I believe it is only a question of preference and the way it sounds.

La neige is just that ephemeral substance while les neiges is more abstract, generic, poetical and somewhat timeless.

It is used in expressions like les neiges d’antan, les neiges éternelles and les neiges du Kilimandjaro. Compare “The Snows of Kilimanjaro” to “Kilimanjaro Snow”, the latter looks like a weather forecast or ski resort ad.