That the creative process is roughly the same - but the corporate attitude and knowledge base can be so very different.
For example, advertising agencies rightly pride themselves on being close to current trends in popular culture and on first name terms with the arts in all forms.
Of course, the dark side of this relationship has been some well-publicised incidents of outright plagiarism.
Even the hallowed halls of Britain’s most creative agencies have not been a stranger to what I’m sure their creatives would call "an homage", but what the rest of us can plainly see is a just a lazy rip-off with a client’s logo stuck on the end.
But on the light side, an intimate acquaintance with what’s happening "out there" can help make a brand famous.
Whether it’s signing an up-and-coming comic to front a campaign or picking a top track from the about-to-be-big band, an injection of street cred can overcome our indifference to commercial messages.
By definition, this is easier said than done. How cool is a piece of music once it’s been pressed into service by, say, a telecoms corporation?
Even worse is when an advertiser claims that their product is somehow "urban" and therefore dripping with gritty metropolitan chic. Yes, Nissan, I am looking at you.
Nissan’s current campaign for their new Juke and Qashqai models is awful on several levels.
One execution has the Juke vehicle bursting out of a collage of faux-trendy posters as if it was "born" in Shoreditch.
Another press ad has a grey Qashqai whizzing along a street, apparently dodging a paint bomber.
Look closely and you’ll see that some of the paint has obscured some unrealistic shop fronts to create the words "urban proof".
What does this even mean? Are bright splodges of emulsion supposed to represent the perils of city driving?
The single paragraph of copy does nothing to explain matters. "More tough, more stylish. Urbanproof. Mastered" pure gibberish.
No doubt the Qashqai is a decent enough motor but it is ill-served by advertising that tries so hard and says so little.
Simon S Kershaw is a creative consultant and a former creative director at Craik Jones.