The gravity and friction of the pulley are not timed. As can be seen from the figure, the pulley hanging A is a moving pulley, which can save half the force, so FA = GA2 = 300N2 =150n; The pulley with B is a crown block, so the crown block is not labor-saving, so FB = GB = 300 N; So fa < FB.

Because objects A and B are lifted at a uniform speed, the position of A relative to the pulley has not changed, so the object with the pulley as the reference is stationary. At this time, the object rises at a constant speed, the mass remains unchanged, and the height increases, so the potential energy (or mechanical energy) is increasing.

So the answer is: less than; a； Potential energy (or mechanical energy).