Paraphrase is defined by McMillan (2001) as an "express[ion] of certain facts and ideas in different wording - your own - but "in the same number of words as the original."
Refer to the Biology program web site (see link below) for examples of how to paraphrase an author's idea(s) correctly. Remember, you must cite a paraphrased idea/sentence(s) in the same way in which you cite a direct quote.
In contrast, McMillan (2001)  defines summary as the "express[ion] of the important facts and ideas in fewer words than the original; for example, the abstract of a research paper is a summary." If you are summarizing an author's ideas, remember to give the author credit!
 McMillan, V.E. 2001. Writing papers in the biological sciences. Bedford/St. Martin's, Boston, Mass.