Assistant
Part of speech: noun
Definition: A person who assists or helps someone else. sales assistant. A software tool that provides assistance in some task.
Part of speech: adjective
Definition: Having a subordinate or auxiliary position.
Example sentence: If you want to get an email to Robert Redford, you send it to his assistant, and she prints it out. And then he will write you a letter, which is incredibly rare and incredibly classy. Unfortunately, I can't be that removed from technology.
Helper
Part of speech: noun
Definition: One who helps; an aide.
Example sentence: I know God's voice. I've seen God's hand. If the Lord is my helper, why should I be afraid?