Another thing to remember, with fat quarters, is that when you go into a store, or order online, 1 fat quarter, the owner has to invest a full half-yard to cut you that FQ.
The other one might sit unsold for a long time, or it may end up being eventually sold at a deep discount. Considering the labor involved in cutting them, and the factors noted above, FQ's are usually a money-losing proposition unless priced considerably higher than yardage prices.