How to distinguish the poor area and rich area on the Google map?

Today

reddit ReTie, a man named the user with a picture shows if the Google map distinguish the poor area and rich area, on the map as follows:

this is a map in the silicon valley, California, USA. The left is the whole foods , the right side is the distribution of wal-mart. The distribution of two distinct to mark the region of the rich and the poor area.

knowledge background:

the whole company (Whole Foods Market) the nation’s largest natural food and organic food retailers , for many customers, they want to health food. However, with the prices of the food is really high, get a nickname: “whole food supermarket” big checks.

wal-mart (walmart) help customers save every cent the purpose, has realized the price is the cheapest commitment. it do anything to from sources, distribution and marketing expenses, administrative expenses and so on various aspects to save money, put forward the slogan of “everyday parity, consistent”, and strive to achieve the promise of cheaper price than other firms.

if in China, what kind of key words should be set up to look at different level of consumption area?