Preponderance of evidence is a more likely than not standard, in other words, if a party can present evidence supporting a hypothesis that is 50+%, or anything more than 50%, then a verdict is entered for that hypothesis. It's used in civil cases. Beyond a reasonable doubt is obviously used in criminal cases. To convict the defendant, the prosecutor has to show there is evidence supporting defendant's guilt that is beyond any reasonable doubt. If there is a doubt of defendant's guilt in the jury's mind that is reasonable, then they must find him not guilty.
