The piece sacrificed deliberately carries a different meaning from the piece simply forgotten.

Two identical losses can mean opposite things depending on whether they were chosen. A piece given up on purpose buys something: position, time, a line opened. The same piece dropped through inattention buys nothing, and the board looks the same in both cases, which is why the record of a game is a poor guide to what was understood.

When something goes wrong, separate the cost from the question of whether you meant it. Deliberate losses are worth reviewing for whether the trade was good; accidental ones are worth reviewing for what you were not looking at. They need different corrections.