A watt in the 288 board produces the same amount of heat as watt in the 120 board.
However,
How the boards handle heat distribution is different. The QB288 is (or was, not sure about the newest US made versions?) 1.6mm thick and the QB120 is 2.0mm thick. The additional .4mm makes the QB120 "run cooler" than the QB288.
The Q288 will be more efficient per lm watt than the QB120 while ran at 60 watts total, but when you factor in the cost and shipping of the boards, power supplies, etc, the QB120 starts becoming a lower cost per lm output to build (at a larger foot print).