Bluegill and Sunfish are very similar in appearance (more so when juveniles) but not synonymous. That fish is a Green Sunfish (Lepomis cyanellus) and not a Bluegill (Lepomis macrochirus).
Well a bluegill is a sunfish, however, all sunfish are obviously not bluegill. Kind of like how all squares are rectangles, but not all rectangles are squares
