"Blink" is about our ability to think without being aware of our thinking. By focusing on what I would call our "unconscious thinking" (think "intution," or think "Freud was right, only his focus was off."). Mr. Gladwell admits that it's not a perfect measure (read on "The Warren Harding Effect" in the book) and he also gives hints on how to correct the wrong impressions that come from such thinking.
"The Tipping Point" is about how ideas and actions spread. From new things becoming hip to crime doing a major collapse in New York in the 1990's, it looks at what happens to cause these things. And again, it's usually the small
Both good and thought provoking books. And each one of them points always to a small thing which ends up having a much greater power in our world than all the big things we think of.