Difference between pointer-to-pointer and pointer

I understand that a char buffer is passed into a function when it has to 
return a string. What I am not very clear about is why does it need a 
char** and not a char* directly.

If memory is allocated for the buffer in either case using malloc, 
shouldn't it work the same? A short working example is pasted below with 
two functions, one of which takes a char** and the other char*.

Appreciate the help.

#include <stdio.h>
#include <stdlib.h>

void getname(char **);
void getname2(char *);

int main(void)
{
	char *c = NULL;
	char *d = NULL;
	
	getname(&c);
	printf("char    - %d\t\t%d\n", *c, sizeof *c);
	printf("char *  - %d\t%d\n", c, sizeof c);
	printf("char ** - %d\t%d\n", &c, sizeof &c);
	printf("---\n");
	
	getname2(d);
	printf("char    - %d\t\t\n", *d); // Crashes here
	printf("char *  - %d\t%d\n", d, sizeof d);
	printf("char ** - %d\t%d\n", &d, sizeof &d);
}

void getname(char **c)
{
	char s[] = "Oranges and Lemons sold for a penny";
	
	*c = malloc(10 * sizeof **c);
	sprintf(*c, "%s", s);
}

void getname2(char *d)
{
	char s[] = "Oranges and Lemons sold for a penny";
	
	d = malloc(10 * sizeof *d);
	sprintf(d, "%s", s);
	printf("char    - %d\t\t%d\n", *d, sizeof *d);
}

Regards,
Pranav Negandhi
www.pranavnegandhi.com