The Hammer and Hanging Man share an identical candlestick shape — a small body with a long lower wick — but signal opposite outcomes depending entirely on where they appear. A Hammer forms after a downtrend and signals a potential bullish reversal, while a Hanging Man forms after an uptrend and signals a potential bearish reversal.
Traders compare them precisely because their visual identity makes them easy to confuse, and mistaking one for the other by ignoring the preceding trend can lead to a trade in exactly the wrong direction.