Generally speaking, second degree doesn’t involve premeditation. You get in a bar fight and kill someone or walk in on your wife with another man and shoot in a blind rage.

Manslaughter is generally when you kill someone criminally without intent. That would be something like running a stoplight, which is a crime, and t-boning a car killing a passenger. You were committing a non-violent crime with no intent to hurt anyone, but you still killed someone.

Felony Murder in many states is when you commit a felony that leads to someone’s death. For instance, you commit arson for insurance money (a felony), and someone gets killed trying to put it out. It’s also been used on robbery accomplices when their partner kills someone.

Depraved Heart Murder is when you knowingly do something so incredibly reckless someone is likely to get killed and choose to move forward. The depraved indifference in that case is considered malice aforethought (essentially intent). An example would be knowingly selling tainted medicine for profit. A great real-life example was the Schlitterbahn executive that paid off injury victims for a dangerous waterside to keep them quiet because the slide was really profitable until a kid was decapitated by the ride. The executive was charged with murder for covering up the dangerous ride instead of shutting down and fixing it.