Q:

What is the difference between sequential access and sequential traversal of elements in data structures

Sequential traversal is the main difference between linear and non linear data structures.Can anyone explain it briefly? 

A:

A linear data structure is something like this:
A
B
C
D
E

For instance, lists and arrays.  Each element is followed by a single element.  Traversal is trivial, as you simply go from one element to the next.  For instance, if you start at A, you only have one next element B, from B you only have one next element C and so on.
A non-linear data structure is something like this:
   A
 /   \
 B    C
/ \  / \
D E  F G

For instance, a tree.  Notice how A is followed by two elements; B and C, and each of them is followed by two elements.  Now traversal is more complex, because once you start from A, you have a choice of going to either B and C.  What's more, once at B, you have a choice of going further down, or going "sideways" to C. In this case (a tree), your traversal options are breadth-first or depth-first.

