How is this different than setting a "Buy It Now" price one penny higher than the starting bid price?
It's different because the fixed-price transaction NEVER has the possibility of becoming an auction. The Buy-It-Now item might be purchased at the set price, but it has the possibility of becoming an auction, too.
This is NOT brain surgery, folks.
Very little really. What type of moron would bid on an auction that he could win on by paying an extra penny?