While I'm not familiar with the specific comparison to which you refer, it sounds as if the term you want is "simile." According to Wikipedia: "A simile is a juxtaposed comparison of two or more objects to draw attention to their similarities. In English, similes are typically marked by use of "like" or "as" or "than", or "resembles". Similes are a specific and formulaic form of allegory."
THEY HAVE BOTH
It depends: in comparison with 5 it is but in in comparison with 5 trillion it is not.
A simile is a comparison of two unlike things using like or as. Example: He ran like the wind, or she as fast as the wind.
metaphor
metaphor
metaphor, comparison, figure of speech
true
similes and metaphors.
When a speaker compares an abstract idea to a concrete image, they are using the figure of speech known as personification. Ideas or concepts are harder to grasp than concrete images. Comparing the two and giving the idea a solid quality, helps to understand the meaning. It can also be seen as a theoretical comparison, or a theoretical figure of speech. Much depends on the circumstances, such as does the comparison make commonsense. It can also be termed a "what if" comparison. For example, what would have been the result of the Confederacy ( a solid, concrete image ) had gained its independence? ( a theoretical comparison )
This is an example of simile. A direct comparison is being made between the brightness of [an unspecified subject] and the brightness of the sun. An example sentence might be:Her smile was as bright as the sun.
A metaphor is a figure of speech, meaning when a word or phrase that ordinarily describes one thing is used to describe another, creating an implicit comparison, as in "a sea of troubles"or "All the world's a stage"
simile a comparison using like or as