In the selection box select the state you’re interested in, when the hotspots load hover over a spot to see the name then click a source spot, then click a target spot a popup will show you the differences.
to see counties, black dots, check the show counties box, so for example you can compare LA to San Diego, or Monterey to Santa Cruz.
You can load additional states by using the dropdown then you could compare Yuma county to Imperial (if you select Calif and Arizona)
if you’re really crazy you could compare counties in the west say Calif to Florida or Massachusetts
Try it you might like it 😊
The site actually does some other cool stuff, but you’ll have to poke around.