Bribery v/s Reinforcement

I always considered bribery and reinforcement were one and the same...
...Until I entered my master's.
It was then that I exactly learned the differences between the two.
And the basic difference being that: in bribery you give the reward even before the work is done and in reinforcement reward is given after the work is finished so that the individual performs the act again wanting to get the rewards continuously.
These two terms entered my mind while listening to the song of 3 idiots...Give me some sunshine...wherein he says 'rishvat dena to khud papa ne sikhaya, 99 marks laoge to ghadi varna chadi':)

Of course, the subject under which the reinforcements were taught (Behaviour Modification) was one of my favourites and I had mastered it very well which proved to be useful later too.