Summary is a useful first step in writing with sources, but it is not the same as synthesis. When you summarize a source, you articulate its basic argument and essential points. You may even begin to evaluate it--asking yourself whether its argument is logically sound, or whether the evidence is broad or persuasive enough. Here is an example of a clear and succinct summary:
Jones (2010) argued that electronic medical records (EMRs) make care for patients more reliable and thorough. The author cited many instances of medication mismanagement and lack of treatment records that could have been avoided with consistently applied EMRs (Jones, 2010). The evidence in the article was persuasive, but Jones did not address the training and implementation costs of such systems.
In this excerpt, the student clearly explained the source's argument (that EMRs increase quality of care) and its evidence (the inconsistent level of care associated with analog records). She even gave an evaluation of the text and begins to put its ideas into a broader context ("the training and implementation costs of such systems"). However, this paragraph still mainly contains summary. This student needs to bring in other sources and begin to let her ideas build on top of the summary.