Random cite describing the difference:

"Prescriptivism is the term used for approaches to language that set out rules for what is regarded as “good” or “correct” usage. Descriptivism is an evidence-based approach to language that describes, in an objective manner, how language is being used. Most contemporary academic linguists are descriptivists, but prescriptivist approaches abound in schools, style guides, internet comment threads, and parental chidings. This case examines attempts to govern, reform, and/or reimagine English."

https://exhibits.lib.ku.edu/exhibits/show/english-language/g...