Hanging Man -- identical in appearance to the hammer, but appears within the context of an uptrend.
Hammer -- a candlestick with a long lower shadow and small real body. The shadow should be at least twice the length of the real body, and there should be no or very little upper shadow. The body may be either black or white, but the key is that this candlestick must occur within the context of a downtrend to be considered a hammer. The market may be "hammering" out a bottom.