What literary device compares two things directly without using "like" or "as"?

The answer is a literary device known as a metaphor. A metaphor creates a direct comparison between two unlike things by stating that one thing is another, thereby highlighting a particular aspect or quality of the first thing. For instance, saying “Time is a thief” suggests that time steals moments from our lives without using "like" or "as," which differentiates it from a simile that does use those words for comparison. This direct assertion enhances understanding and creates a more vivid image in the reader's mind.

In contrast, the other options represent different literary devices: a simile shows comparison using "like" or "as"; allusion refers to an indirect reference to a well-known person, event, or work; while personification attributes human characteristics to non-human things. Metaphors, however, stand out for their ability to create strong visual or emotional connections through direct equivalency between distinct entities.