Answer: They are different for criminal and civil cases because the legal standard for deciding the criminal outcome follows a different method.
In beyond reasonable doubt, the standard for deciding a criminal charge requires evidence that is sufficient to eliminate any doubts a reasonable person might entertain about whether a claim is more likely to be true than not.
In preponderance of evidence the legal standard for deciding the outcome of civil disputes, requires the evidence to be sufficient that a claim is more likely to be true than not.