Allegory usually is a physical representation of abstract ideas or principles by characters or events in a narrative. Figurative is on a simpler level. Figurative language consists of sounds. The sounds, which are the figurative language, are sufficient to identify an actual event which is already real in itself.
The St. Paul Center for Biblical Theology is helpful:
"How are we, sophisticated, 21st-century Catholics that we are, supposed to read the account of Adam and Eve’s fall from grace in Genesis 3 - with its fable-like setting, its talking trickster snake, its gullible couple, oddly named trees, and forbidden fruit?
The Catechism of the Catholic Church gives us some good advice here:
“The account of the fall in Genesis 3 uses figurative language, but affirms a primeval event, a deed that took place at the beginning of the history of man. Revelation gives us the certainty of faith that the whole of human history is marked by the original fault freely committed by our first parents” (see no. 390).
What’s the Catechism getting at here? First, the story in Genesis 3 is written in “figurative language” - it’s more like poetry than journalism, more like a painting than a documentary film.
Nevertheless, the story “affirms” an actual event that indeed “took place” at the beginning of human history. What’s more, that event, “the original fault” of Adam and Eve, forever “marked” human history.
We can’t, then, read Genesis 3 like we’re reading a newspaper. But we can’t read it like it’s a myth or a fairy tale or a fable - as if it’s about something that never happened.
Scholars tell us that Genesis is best understood as an example of the ancient literary style know as mashal - “a riddle” or a “proverb” in which there are layers of double meaning.
And when we read Genesis 3 closely, we find the story turns on a number of tricky passages, and words filled with multiple meanings: life, death, wise, trees."
The above comes from
stpaulcenter.com/studies/lesson/lesson-two-creation-fall-and-promise