What is difference between uninitialized pointer and null pointer?

Question

What is a NULL Macro? What is the difference between a NULL Pointer and a NULL Macro?

Answer 1

Uninitialized pointer may contain garbage value and accessing an invalid address may cause segmentation fault.
Programmers always guard invalid access of pointer by putting cross check against the NULLP. As per good programming practices always assign NULLP to a pointer which does not hold a valid address.
Example:
int *p ; // uninitialized pointer
int *p = NULL; // initialized with NULL.

Answer 2

int* ptr = NULL; //Is this going to avoid the problem
This will cause ptr to point to NULL which you can explicitly check for as a default/uninitialized value. It prevents the problem, but a careless programmer can still accidentally dereference a null pointer without checking, causing undefined behaviour.