An extract takes portions of a document exactly as it is, while an abstract summarizes important details. With the latter, you can personalize the information as you wish.
Similarities between extracts and abstracts
- Both must have a full citation of the document
- Both use quotations but are more prevalent in extracts
- Indicate text you have left out using ellipses (…), most commonly in extracts
- Square brackets  indicate short comments, and incorrect facts, spellings, or information you are aware of but choose to leave as per the original document.
Why and When to prepare extracts and abstracts
- When you cannot make scans, photocopies, or take photographs.
- For inclusion in reports or notes
- When you need to pinpoint important details
- Important when developing research plans or analyzing documents
- Unlike a full transcription, they are very concise, especially if you’re working with little space