with Mike Brown, they outright said he was unarmed, but say Wilson thought he might have had a gun. you can't prove that Wilson didn't think that, unless he confesses otherwise.

with Sean Bell, they said they thought he had a gun. you can't verify what people think.

in this case, they said he had a gun that they recovered on the scene, and that he fired three shots at the officer. both of those things can be tested and verified, which leaves far less wiggle room.