Two present verb tenses:

Present tense with "is" and "are": Paul is a salesman. Myra is a store manager. Paul and Myra are sales people.

Present simple tense with "do" and "does": Does Patty deliver mail? Yes she does. She delivers mail.

Paul sells things door to door. He is a salesman.
Myra manages a store. She is a store manager.

Questions with Who as subject:
Who sells goods door to door? Paul does.
Who is a postal worker? Patty is.