What is the difference between an attempted escape and a conviction under section 4532 of the Penal Code?

As the opinion on the first appeal points out, defendant had been charged, in a single count, with violations of both subdivision (a) and subdivision (b) of section 4532 of the Penal Code. In our judgment, we referred to section 654 to emphasize the fact that, since there was only a single attempt to escape, only a single punishment could be imposed even though both subdivisions of the section were applicable. We cited People v. Siegel, since that case had held that, in view of the terms of section 4532, an attempted escape was punishable under it and not under section 664 (the general attempt

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