Map[{InputForm[#], FullForm[#], Head[#]} &, {2, 2.0, 2/3, 2 + I/3, x, 
          x + y, 2 x y, {1, x, z}, Sin[x], Exp[x], Sqrt[x]}] // 
      MatrixForm

{{"12/4", 12/4}, {"5!^3/10!", 5!^3/10!}, {"Exp[x]", 
          Exp[x]}, {"Exp[0]", Exp[0]}, {"Exp[1]", 
          Exp[1]}, {"Sqrt[9]", Sqrt[9]}, {"Sqrt[10]", 
          Sqrt[10]}, {"Sqrt[10]^2", 
          Sqrt[10]^2}, {"(1+I)(1-I)", (I + 1) (I - 
                1)}, {"(x+y)(x-y)", (x + y) (x - 
                y)}, {"Product[k,{k,1,5}]", 
          Product[k, {k, 1, 
              5}]}, 
{"Product[k,{k,1,n}]", 
          Product[k, {k, 1, n}]}, 
{"Sum[k,{k,1,5}]", 
          Sum[k, {k, 1, 5}]}, 
{"Sum[k,{k,1,n}]", 
          Sum[k, {k, 1, n}]}, 
{"Sum[a[k],{k,1,n}]", 
          Sum[a[k], {k, 1, n}]}, {"Integrate[Sin[x],x]", 
          Integrate[Sin[x], 
            x]}, 
{"Integrate[Sin[x]/Log[x],x]", 
          Integrate[Sin[x]/Log[x], x]}} // MatrixForm