Embezzlement under California law is the "fraudulent appropriation of property by a person to whom it has been entrusted." This used to be considered a distinct crime. But now California law treats embezzlement--and punishes it--merely as a variant of theft.
Embezzling property up to $400 in value gets prosecuted as a petty theft. Embezzling more than $400 worth of property may be punished as a grand theft. The former is a misdemeanor with a maximum sentence of a year county jail. The latter may be charged as a felony and can land someone in California state prison for up to three years.
So if they're charged under the same section, what's ultimately the distinction between embezzlement and standard theft offenses? The answer lies primarily in how the crimes get viewed by prosecutors, judges and juries.