Difference between files written in binary and text mode

What translation occurs when writing to a file that was opened in text mode that does not occur in binary mode? Specifically in MS Visual C.

unsigned char buffer[256];
for (int i = 0; i < 256; i++) buffer[i]=i;
int size  = 1;
int count = 256;

Binary mode:

FILE *fp_binary = fopen(filename, "wb");
fwrite(buffer, size, count, fp_binary);

Versus text mode:

FILE *fp_text = fopen(filename, "wt");
fwrite(buffer, size, count, fp_text);