The difference between Rawls and trickle down capitalism is, as I see it, the following.
Imagine a society where everyone (100 people) has 100 dollars. Let's say that the government decides to invest some money in soybean production, and compensate the soybean peasant pay a slightly higher rate so taht he'll be copvered in case his crop fails, and to compensate him for teh extra labor and uncertainty that planting a new crop involves.
Let's say that now society has 90 people with 101 dollars, and 10 wealthy soybean producers with 111 dollars. The extra 200 dollars was created because soybeans are more nutritious than cassava or whatever they were growing before, and therefore has a greater value to society in terms of minerals, vitamines, protein, etc.
Let's say now that the government determines that the soybean producers are willing to raise soybeans if they get a mere 2.50 dollars extra. Below this, they would rather not do it. (If the government owned teh soybean plantation, that woudl be good, but I don't think it would make a major difference. The government planners just like peasants woudl need a little extra cash to cover losses if teh soybeans didn't work out.) This would leave 1.75 dollars for everyone else.
In a trickle-down philosophy, Option 2 is justified because the poor are better off than they would be before the soybean experiment. But to a Rawlsian, option 2 is unjust because the poor are WORSE OFF than they would be in option 3. In otehr words, Rawls allows only inequalities that make the poor better off than in ANY OTHER system. Trickle down capitalists endorse any change that makes the poor (supposedly) better off than they were before. Trickle down justifies inequality by syaing the poor are better off than if the production taht generates inequality ahd NEVER OCCURRED> Rawls, on teh other hand, says that inequalities are only jsutified which amke teh poor better off than under any more socialized system. We should, in otehr world, socialize production to teh point where the standard fo living fo teh poor reaches its maximum. This is, as far as I acn see, incompatible with any mroe than teh very absrest minimum of private ownership.