Summaries tend to be interpretive. They give the author's critical evaluation of the source. Would your summary differ, for example, from the following summary of The Wizard of Oz? Transported to a surreal landscape, a young girl kills the first woman she meets and then teams up with three complete strangers to kill again.
Like paraphrasing, summarizing involves reporting someone else's ideas in your own language. Unlike paraphrasing, however, summaries allow you to sort through the information in the secondary source and report only what you consider to be essential. A summary is therefore much shorter than the original, whereas a paraphrase may be the same length. In addition, you do not need to cite particular pages when summarizing a source.