
Max M. answered 06/13/19
Harvard Literature major with 20 years of coaching writers
As opposed to literal, yes, but since it uses a direct comparison word (like / as), it's a simile, not a metaphor.
It took me a long time to wrap my brain around why the difference was important, even after memorizing that similes have "like" or "as" and metaphors don't. Maybe this will help--I think it would have helped me.
Similes are comparisons--"this is like that." Because of this, I find there's something direct and straightforward about them, even if they're poetic and vivid, like this one is. And they often, but not always, make only one point of comparison. Mercy is like rain in the gentle, easy way it falls from heaven. Jessica isn't going into this mercy / rain thing any more than that, and she doesn't want you thinking about it forever, because she has a point to make, and she wants to get on with it!
Also think about when Forrest Gump says "Life is like a box of chocolates," he immediately explains what he means: "you never know what you're gonna get" (which isn't true, but it's still a solid example of a simile).
Metaphors tend to be deeper. You start talking about a thing as if it actually were something else. This can make the comparison multi-faceted, since you're saying "this IS that." And you start to see things in a completely different way. In "As You Like It," Shakespeare has a character say, "All the world's a stage," and then describes in detail the vision of life that follows from that idea.
You might not even have to make the comparison explicitly. When Hamlet wonders about the "slings and arrows of outrageous fortune," he doesn't even need to say, "fate is an attacking army," (much less "fate is like an attacking army"); he makes you see it that way by talking about fortune's weapons, and bam! you're in his worldview before you know it.
For a more modern (and more lighthearted) example, when Meghan Trainor sings "I'm all about that bass ('bout that bass...), no treble," she doesn't say "women's behinds are like the low notes in a piece of music;" but she makes you see it that way, along with everything that implies, rather than listing every point of comparison.