A Stop Loss and a Trailing Stop are both risk-management orders that automatically close a position, but they behave differently as price moves. A stop loss sits at a fixed price level and stays there for the life of the trade, while a trailing stop adjusts automatically in the favorable direction as price moves, locking in gains along the way without ever moving backward.
Traders compare the two because they solve different problems — a stop loss defines your maximum acceptable loss, while a trailing stop is designed to protect profits on a winning trade as it develops.