Alliteration has same starting consonants. Ex. "Shelly sold seashells down by the seashore." Notice the majority of the word start with S.
Personification is humanizing something. Ex. "Lightning danced across the sky." Humans dance and here we are comparing the movement of lightning to the movement of dancing people.
Metaphors are comparisons of two things, non living.
"She has a heart of gold", its just a figure of speech because people cannot have hearts of gold, just like the the "it" cannot actually burn with topaz light because topaz does not actually have a light.
