Difference between putback() and unget()

I'm using a Standard iostream to get some input from a file, and I'm confused about unget() versus putback(character). It seems to me from the documentation that these functions are effectively identical, where unget() just remembers the character put in, so I'm nervous. I've always used putback(character), but character is always the last read character and I've been thinking about changing to unget(). Is putback(character) always identical to unget(), if character is always the last read character?