unsigned is a modifier which can apply to any integral type (char, short, int, long, etc.) but on its own it is identical to unsigned int.
unsigned
char
short
int
long
unsigned int
There is no difference. unsigned and unsigned int are both synonyms for the same type (the unsigned version of the int type).
unsigned alone means unsigned int. You can also use unsigned char, etc. I have no idea what happens if you try unsigned double or unsigned float. Anybody know?
unsigned char
unsigned double
unsigned float