Dmitry, Will you learn English? It is a direct question about someone’s definite or formal plans Will you drive your Porsche to Moscow? Will you be learning English? This refers to a less definite plan or to an intention. The future continuous can be used for a polite inquiry about someone’s plans. -Will you be learning English? -Will you be having wine with your steak?

The sentences are in essence, the same. "Will you be learning English?" is just a longer way to say "Will you learn English?" The one case where you might use them differently is, for example, if you are going to America or an International School, someone might ask you, "Will you be learning English?" as an extension of your trip or education, rather than simply learning English on its own or for its own purposes.