Some are regionally different:
- New England
- Coastal California
Some are urban areas surrounded by urbanized and/or high-education suburbs:
- New York City
- Baltimore/Washington, D.C.
- Seattle, WA
- Portland, OR
- Kansas City, KS and MO
- Detroit, MI
- Chicago, IL
Some are just cities themselves:
- Dallas, Houston, and Austin, TX (blue counties in a sea of red)
- Pittsburgh, PA
- Cleveland and Columbus, OH
Some are Hispanic:
- Southern California (and yes, this overlaps with coastal California)
- Nevada (parts)
- Southern Arizona
- New Mexico
- Texas border with Mexico
- Colorado (parts)
- Some Miami suburbs and neighborhoods
Some are African-American:
- Mississippi river area
- Appalachian foothills (Mississippi to Virginia)
As discussed in the other question, there are really three areas in the green: African-American, urban, New England.
That's also true of the other areas. Seattle, WA, coastal California, and Southern Arizona are all in the blue but have different reasons. Some of the yellow is just cities, while other parts are Hispanic and the Northern portions have their own basis. Montana, Wyoming, Idaho, and Utah have relatively small populations, so relatively small enclaves of Democratic voters can swing a county. In the pink, Michigan, Indiana, Illinois, and Wisconsin are primarily Democrat in cities. But Minnesota and Iowa have more rural areas.
The one semi-constant is population. Even in places like Wyoming, it's the urban areas that vote Democrat. The difference in Wyoming is that a large town or small city may make up most of the population of the area. In sort of medium populated areas like Pennsylvania, Kansas, or Louisiana, such small urban areas are outweighed by the rural population. It's only the larger cities that show up as blue counties.
Minorities were more likely to vote for Clinton. Higher educated people were more likely to vote for Clinton. But both tend to clump in or near cities. It's only a few other areas where they make a real difference.
Women were also more likely to vote for Clinton but are spread out much the same as men. Not useful for explaining trends in counties or map regions.