I have not yet been verified (info sent), but I have been practicing criminal law in the tri-state area for over six years.
In short, PL 125.25 (second degree murder) blanket covers the intentional killing of another. It is more commonly used than PL 125.26 (aggravated murder) and 125.27 (first degree murder). PL 125.27 also covers intentional killings, but it requires some other special circumstance to be present (such as the victim being LE, a judge, firefighter, etc.; felony murder; contract killing; etc.). Aggravated murder is an intentional killing of a specific type of victim (LE, fire, etc.), but the statute significantly overlaps with first degree murder. 125.27 is about special circumstances, and 125.26 is specifically about the victim.
125.25, 125.26, and 125.27 are all A-I felonies with similar penalties.