Dean’s protective gesture: Sam, look out, be careful.
Sam’s protective gesture: Dean, don’t do anything stupid.
I just love the difference in the brother’s relationship. Dean is the protector, all his life he’s been protecting Sammy from everything, from demons to cars speeding down the road. But Sam is used to protecting Dean in a different way. Dean’s always been the shoot first, ask questions later type of hunter and he came by it honestly, with their Dad drilling it into him from a young age. Sam however ignored that particular order and he’s able to see when a situation demands a different approach.