The bright green areas are: "highly educated, young to middle aged population who tend to live in rented accommodation located a short distance from Central London. They tend to work 49 hours or more a week."
The blue/green areas (like the one next to the pointer) are home to: "a young population who tend to both live and work in Central London. They are most likely to live in rented accommodation and least likely to own a car."
In purple live: "the most well off of all the Whereabouts with the highest proportion of company directors this West London group have the highest proportion of degree level qualifications."
While in red: "a professional and well educated population mainly residing in outer London. They are more likely to commute to work via train."
We also have a small group in pink who: "tend to be the most evenly distributed, located across inner and central London. They have the highest proportion of those in care and leisure occupations."
Much more data geekery can be found at the Whereabouts website.