What is the difference between voluntary and involuntary manslaughter?

The Attorney General argues that Dewberry is not applicable as between voluntary and involuntary manslaughter, since involuntary manslaughter is not a lesser-included offense of voluntary manslaughter, citing People v. Orr (1994) 22 Cal.App.4th 780 (Orr) (decided in a double jeopardy context). The Attorney General is correct. As explained in Orr, voluntary and involuntary manslaughter are two kinds of manslaughter; involuntary manslaughter is not an included offense of voluntary manslaughter. Voluntary manslaughter can be committed without necessarily committing involuntary manslaughter, as the "definition of unlawful as an element of involuntary manslaughter differs significantly from that of voluntary manslaughter and requires the trier of fact to make substantially different findings." (Id. at p. 784.) Defendant first responds that the holding in Orr was made in the context of double jeopardy; while true, that does not detract from its reasoning. Defendant then argues that the fact that involuntary manslaughter is not a necessarily included offense of voluntary manslaughter does not necessarily bring this case out of the ambit of the requirement of a Dewberry instruction, as that instruction must also be given with regard to all crimes with lesser degrees (not the case with manslaughter) or related offenses. Involuntary manslaughter, defendant argues, is a related offense of voluntary manslaughter.