A metaphor is undoubtedly an implied comparison, as in "the silk from the singer's voice." This is in distinction for the explicit comparison with the simile, which employs like La nieve en sus cabellos hablaba de su historia. (Las canas se comparan con la nieve porque ambas son blancas) Plenty https://www.youtube.com/watch?v=dRuXZtV7Wsk