Plain English Meaning
Errors are the things a pilot does wrong in the cockpit or in training. Sometimes you knew what to do but your hand did the wrong thing (a slip). Other times you did exactly what you intended, but the intention itself was based on faulty thinking (a mistake).
Full Definition
In aviation instruction, errors are actions or inactions by a pilot or learner that lead to deviations from intentions or expectations. They are typically grouped into two categories: slips, which occur when a person plans the right action but executes it incorrectly, and mistakes, which occur when a person executes the planned action correctly but the plan itself was wrong.
Context Anchor
Seen in aviation instruction, debriefing, safety discussions, and any situation where a pilot compares what happened with what should have happened.