Both poets are talking about the snow. However, Dickinson did not identify the snow. She only used the pronoun "it" in describing the snow. Emerson provided clarity when he said "arrives the snow".
The mood of It sifts from Leaden Sieves is very calm and soothing whereas the mood of The Snow-Storm is very wild and tumultuous.<span />
D.. I think. Although it's long, it best expresses the meaning of the two sentences it combined.
The central idea revolves around that question. Is 16 too young to drive a car? It presents evidence, facts, and arguments to make the point of either 16 isn't too young or 16 is too young.<span />