They're spreading! ........? I think the difference is just these come out in groups every 10 to 17 years depending upon the broods.I know they say brood x is a primarily east coast thing but I found one in my garden lookin just like bo's pics out here in cali.
You would notice if it was periodical cicadas. Especially if you have trees ? on your land. You would see mounds/tunnels in your yard . I had them everywhere in the backyard. We have a few huge maple trees.
Once the ground hits a 64degree average. They all come out at once , molt into adults and leave their exoskeletons everywhere. I was showing those cicadas I took pictures ? of to my niece. She was picking them up, that kid loves her some bugs ? , if you let her know they don't bite hehe