One of my favorite ads was for Rolling Rock beer, ca 1996: "Here's to subtle differences." Rolling Rock uses slightly more malt for a little more body, a little more bite, and they're encouraging you to appreciate that the next time you imbibe. There were several versions in the campaign, but the one I found most effective was "the look":

You see what I mean.

The power of subtle difference came to mind in the recent scandal that lead to the resignation of Scott Thompson at Yahoo!, centering around a slightly fudged resumé.

If you ask me (and you didn't, but here you are): something subtle turned me off of the brand of Scott Thompson when I saw the picture from his Yahoo! bio page that accompanied many of the recent news stories. It was a subtle difference that affected me, as a consumer of news, as a consumer of the services and therefore the brand of Yahoo! Here it is:

If I had seen more of the official photo on the left, I might have been less unsympathetic (subtly different from "more sympathetic") to Thompson and his plight. However, I saw much more of the official photo on the right, on his Yahoo! bio page and in many of the news stories about his deceit. Do you see the difference? I do. A slight upward tilt of the head, shot from a slightly lower angle, in a classic pose of superiority, arrogance, perhaps looking down his nose at you. It's there, and in that 50 milliseconds it takes to determine a level of trust in a brand, that subtle difference made a difference to me.

This plays out every day at every touchpoint of your brand. We've done both subjective and ultra-objective testing of the many factors leading to successful web design, and it is often the most subtle differences that make or break the day.