Difference between Malloc vs Realloc

Difference between Malloc vs Realloc.
Malloc(n) allocate memory dynamically on the heap. Realloc(ptr, n) change the memory size of existing allocated memory. If n is greater than the old size and if sufficient space is not available subsequent to the old region, the function realloc( ) may create a new region and all the old data are moved to the new region.