A simile is a figure of speech that compares two unlike things using connecting words such as like or as—for example, “cheeks like roses.” A metaphor also suggests a likeness, but it does so more directly by applying a word or phrase from one thing to another without those connectors—for example, calling someone’s cheeks “newly bloomed roses.”
In short: similes signal the comparison explicitly; metaphors assert the likeness by treating one thing as if it were the other. Both are everyday tools of description, not only poetry devices. (Merriam-Webster)