Excerpt: This refers to a short passage taken from a longer work, usually to illustrate a point or provide context. Think of it as a "snippet" or a "sample."
Extract: This has a broader meaning. It can refer to a portion taken from anything, not just text. It could be a chemical extract, a financial extract, or even a musical extract.
Example:
* You might read an excerpt from a novel in a book review.
* A scientist might create an extract of a plant to study its properties.
In summary:
* Excerpt is typically used for a short piece of writing taken from a larger work.
* Extract has a broader meaning and can apply to anything taken from a whole.
While you can often use these words interchangeably, using "excerpt" when you're specifically referring to text is more precise.