Photos confirm that these are two different individuals (some 20 miles apart).
The Tinley Park bird that I found on 22 May 2015:
Compared to the Tinley Park bird, the Chiacgo bird ("The Colonel") has more black on the face as well as a heavier bill. Looking closely at the wingtip pattern, the Chicago bird also has a larger mirror on p10 that spans across both webs of that feather, from edge to edge. The Tinley Park bird has a rounder mirror that's enclosed in black, not reaching the edges of the feather.
I don't know of any other records where two of these putative hybrids have been sighted in any state during the same season let alone the same week. One has to wonder if these two are related, and whether there's a pure Laughing Gull that has taken up permanant residency in one of the lower Lake Michigan Ring-billed colonies. Whatever the case, this is one gorgeous hybrid that steals the show when it flies in!