What is the difference between specific and general intent in criminal law?

"Specific and general intent," we have cautioned, "have been notoriously difficult terms to define and apply...." (People v. Hood (1969) 1 Cal.3d 444, 456, 82 Cal.Rptr. 618, 462 P.2d 370.) The standard formulation of the two concepts appears in Hood: "When the definition of a crime consists of only the description of a particular act, without reference to intent to do a further act or achieve a future consequence, we ask whether the defendant intended to do the proscribed act. This intention is deemed to be a general criminal intent. When the definition refers to defendant's intent to do some further act or achieve some additional consequence, the crime is deemed to be one of specific intent." (Id. at pp. 456-457, 82 Cal.Rptr. 618, 462 P.2d 370.)