The criminal legal opinion you mentioned is not a specific legal document and has no fixed object. It just puts forward its own legal opinion according to the case. It can be sent to the court, such as the legal opinion of the complaint, or to the other party or the procuratorate, which is similar to defense or defense.
The difference between criminal legal opinions and defense opinions and defense words lies in the different scope of application. The former has a wider scope of application and can be used not only in court trials, but also in court trials.