-> make reference to ancient looking ui, gets downvoted.
The difference might not matter in places like where I'm from, where Phoenix blends into Glendale or Mesa or whatever. In Seattle it does feel more like two nearby cities than one mass of suburbs, though, since there's a big physical boundary (Lake Washington) between them.
Edit: Further muddying the waters, I kind of lump the Eastside into one "city" from a geographical perspective, though legally it's Bothell, Kenmore, Redmond, Bellevue, etc. I do think of Seattle as a separate thing.
It seems that people do this in conversation by default already, even if the legal boundaries don't conveniently match with what they mean.
As a BHS graduate, this kind of got me. We are clearly "north" of the lake, and more apart of Everett than say Bellevue.
Bothell is basically equidistant from Seattle, Everett, and Bellevue (I was living in Snohomish County, so closer to Lynwood and Everett), basically under all those cities's influences.