Java中静态和非静态初始化块的研究

我原本以为静态块是用于静态变量的,但编译器允许A和B编译和运行,这会带来什么?
A.

   private static final Map<String,String> m = new HashMap<String,String>();

        {
            m.put("why", "does");
            m.put("this","work");
        }

B

 private static final Map<String,String> m = new HashMap<String,String>();

        static{
               m.put("why", "does");
               m.put("this","work");
             }

System.out.println(Main.m.toString()); A.

{}

B

{这=工作,为什么=做}