What is the difference between a jury finding a defendant guilty of heat-of-passion manslaughter and finding him guilty of manslaughter?

Indeed, the fact that the jurors convicted defendant of heat-of-passion manslaughter shows they did not find the homicide justified by self-defense. The jury was specifically instructed not to convict defendant of any crime if they found the killing was justified by self-defense. Yet, they convicted defendant of heat-of-passion voluntary manslaughter. Because "we presume jurors understand and follow the instructions they are given" (People v. Buenrostro (2018) 6 Cal.5th 367, 431), it is clear the jury rejected defendant's claim of complete self-defense.