Differences in layout between memory and storage

- More explicit description with two examples
- Moved index pointer to correct file

docs/internals/layout_in_calldata.rst

@@ -1,3 +1,6 @@
+
+.. index: calldata layout
+
 *******************
 Layout of Call Data
 *******************

docs/internals/layout_in_memory.rst

@@ -36,4 +36,37 @@ elements.
   definitely zeroed out memory area, using such a pointer non-temporarily
   without updating the free memory pointer can have unexpected results.
 
-.. index: calldata layout
+
+Differences to Layout in Storage
+================================
+
+As described above the layout in memory is different from the layout in
+:ref:`storage<storage-inplace-encoding>`. Below there are some examples.
+
+Example for Difference in Arrays
+--------------------------------
+
+The following array occupies 32 bytes (1 slot) in storage, but 128
+bytes (4 items with 32 bytes each) in memory.
+
+::
+
+    uint8[4] a;
+
+
+
+Example for Difference in Struct Layout
+---------------------------------------
+
+The following struct occupies 96 bytes (3 slots of 32 bytes) in storage,
+but 128 bytes (4 items with 32 bytes each) in memory.
+
+
+::
+
+    struct S {
+        uint a;
+        uint b;
+        uint8 c;
+        uint8 d;
+    }