In simple terms

You see a gorgeous girl at a party.
You go up to her and say, “I'm cute, marry me.”
That’s Direct Marketing.

You see a gorgeous girl at a party.
You go up to her and get her telephone number.
The next day, you call and say, “Hi, I’m cute, marry me."
That’s Telemarketing.

You’re at a party with a bunch of friends and see a gorgeous girl.
One of your friends goes up to her and pointing at you says,
“He’s cute, marry him."
That’s Advertising.

You’re at a party and see gorgeous girl.
She walks up to you and says, "You are very cute, can you marry me?”
That’s just me.