A hill has nothing to do with it. At some point if the hill is steep enough (on the down grade) the 32 will stay in the power longer than a 36 before it winds out. Now if you are building a hill climbing bike a larger sprocket will have more power to get up the hill. The 36 will have more torque to CLIMB and out perform a 32 on a up hill battle.
So lets keep this on flat land for sake of getting you too confused....(just a fun jab)
The smaller the sprocket the faster the top end speed will be, the larger the sprocket the faster the acceleration will be. This is assuming the front sprocket stays the same. Pure physics.