This, I supposed, is a response to Batman's famous quote: It's not who you are underneath, it's what you do that defines you.
Hence, we have "who you are defines what you do" vs. "what you do defines who you are".
I see the relativistic element in these two. In other words, both parties are usually intelligent enough to agree with the opposite statements.
So what's the deal? I would say it's a matter of practicality. The former statement indicates the reformed identity while the later declares the will to act. The latter could accuse the other of hypocrisy just as much as the other accusing the latter of depravity.