This question has been asked so many times and answered so many times in text books that I thought you may appreciate an alternative look at it.
When the circus comes to town and you put up a sign, that’s advertising.
If you put the sign on the back of an elephant and you march the elephant through town, that’s sales promotion.
If the elephant, still with the sign on his back, tramples through the mayor’s flower garden and the television cameras record and broadcast the event, that’s publicity.
If you can get the mayor to laugh about it, that’s public relations. And if you planned the elephant’s walk, that’s marketing.
An alternative version of the circus coming to town – Imagine you walk into a bar and across the room you see a beautiful woman.
If you were in advertising you would march right up to her to tell her how wonderful you are, how you are the partner of her dreams and are going to make her life like heaven on earth.
If you were in marketing then you would plan your approach. First you would strike up a conversation and attempt to find out her idea of perfect partner. Then you would go away and have a make-over before coming back and explaining that you’re exactly what she’s been looking for.
However the public relations professional would simply take a seat at the bar and order a drink. The beautiful woman would soon approach you and breath sexily into your ear: "I’ve heard how wonderful you are and I’d really like to get to know you."
You’re at a party.
If a member of the opposite sex tells you he/she is a great lover, that’s advertising.
If a member of the opposite sex asks you about your bedroom "interests" and shows how he/she fits the profile, that’s marketing.
If a member of the opposite sex walks up to you and says "I hear you’re fantastic in bed" — that’s PR.
And that is when you know that your Reputation Building efforts are working….All that practising, reading the Kama Sutra……