The psychological difference is that people react differently depending on whether the fee is seen as "not receiving a bonus that other people got", or "taking

The psychological difference is that people react differently depending on whether the fee is seen as "not receiving a bonus that other people got", or "taking a pay cut when others didn't." If that doesn't make sense to you, I highly recommend that you pick up a copy of "The Paradox of Choice," a book that lays out neatly how the human brain can be manipulated by simple restatements like this.