What is the difference between Advertisement, Marketing, Public Relation and Branding?

If we ask this question to an MBA graduate or someone pursuing some business administration courses we will fed up with the answers. They will shower full theory from the books Kotler and Bratton. But if we ask to explain the same in simple words, 99% of them will fail. But here comes the simple explanation of the same in simple words. This simple definitions  come from one of my great friends.

I am Merlin; I am a good gal —-Marketing

Merlin is a good girl… Merlin is a good girl…. Merlin is a good girl… Merlin is a good girl….… Merlin is a good girl——-Advertisement

You know Merlin is a good girl——-Public Relation (to a third person)

Yes; I know Merlin is a good girl——–Branding(to a third person)