What are the differences between an array of char pointers and a 2D array?

Question

What are the differences between an array of char pointers and a 2D array?

Answer 1

Array of arrays (aka multi-dimensional array) looks like (in memory):

a[0][0], a[0][1], a[0][n-1], a[1][0], a[1][1], ..., a[1][n-1], ..., a[m-1][n-1]

array of pointers looks like:

p[0], p[1], ..., p[m-1]

where each slot is a pointer and can point to whatever. If they all happen to point to arrays with n elements each, then p[i][j] and a[i][j] can be used similarly in expressions, but they're actually quite different objects.