Snow blocks are blocks made from snow, they are crafted from four snowballs , meaning that you can make them in your inventory.
Destroying them with a shovel yields 4-6 snowballs.
Water or lava cannot destroy snow blocks.
Snow blocks will hinder the snowfall.
Torches will not destroy snow blocks.
Snow blocks do not seem to have any use, like other blocks crafted from other things, and is purely decorative. The main thing about snow blocks is that they do, in fact, look like snow, and can thusly blend in with it. They are the cheapest blocks that can be crafted, producing more material when destroyed than required to create one.