Sentencing guidelines are non-binding guidelines that inform sentencing in law. By contrast, mandatory sentencing sets legal parameters, typically minimums, for sentences.
In the United States federal courts system, Federal Sentencing Guidelines apply to federal judges adjudicating cases in federal court. In England and Wales, the Sentencing Council (formerly the Sentencing Guidelines Council) sets sentencing guidelines.
References
Sentencing guidelines Wikipedia(Text) CC BY-SA