An allusion is a reference to something famous. This line is referencing Titan, a Greek god character:
From forth day's path and Titan's fiery wheels:
A simile compares using like or as:
Without his roe, like a dried herring: flesh, flesh,
how art thou fishified!
Mercutio says this about Romeo comparing him to a fish that just flops around.
A metaphor states something as if it is something else:
The earth that's nature's mother is her tomb;
What is her burying grave that is her womb,
Here, a hole in the earth meant to bury someone is compared to a woman's womb.