To call Jimmy McNulty and Bunk two sides of the same coin would not be very accurate. They’re more like a Venn Diagram. They’re both good cops, they both work their cases, and they both care about what’s happening to their city. While the off-again/on-again partners share all these traits, where they differ is what defines their relationship. A relationship that was crucial to their professional successes, their personal failings, and the triumph that was, The Wire (which you can stream in full on HBO NOW).
The fundamental difference is that Bunk is able to understand the chain of command, and, more importantly, how to follow it. McNulty, on the other hand, lets his passion get the better of him, and while he’s aware of the chain of command, he seems incapable of following it. Basically, Jimmy’s “good police,” but also a back-burning loose cannon who Bunk regularly scolds for “giving a f*ck when it’s not your turn to give a f*ck.”