what is the difference between formal and informal language?

informal language is used by professionals
or
formal language uses more varied and complex vocabulary
or
informal language uses jargon
or
formal language uses contractions, slang, and personal pronouns

The correct statement is: formal language uses more varied and complex vocabulary.

Formal language is more structured, professional, and appropriate for academic or professional settings. It typically avoids contractions, slang, and personal pronouns. It is characterized by the use of precise and complex vocabulary, longer sentences, and a more objective tone.

On the other hand, informal language is more relaxed, casual, and used in everyday conversations or less formal situations. It often includes contractions, slang, and personal pronouns. Informal language communicates in a less structured and more conversational manner. It may also incorporate jargon or specific vocabulary used within certain groups or communities.