Both are the same Greek word. Paul had to learn as he went. He did not have the advantage of learning from Jesus. Most of what we read in his writings, he learned from the Holy Spirit by revelation. Paul asked three times for God to remove the burden of this tormenting messenger of Satan.
Fear is the opposite of faith.
Fear, will open a gate in the hedge. A gate that the Satan will enter if it is open. Job became highly blessed by God, prospering in every way. And God had made a hedge around Job and all that he had. Job was almost flawless in his obedience to God.