The Summary is a short description of another text, in which the text’s central ideas are identified. In some fields, and for some shorter assignments such as Lab Reports, a Summary may take the place of an Abstract, and be presented at or near the beginning of the text. A longer, more formal work like a thesis may have both an Abstract (at the beginning) and a Summary (at the end).
A Summary is a short description of a text’s central ideas. A Summary may be a stand-alone text or one or more summaries may be given as part of a larger text; for example, a long text like a thesis may have a Summary for each chapter. A thesis can have both an abstract (at the beginning) and a Summary (usually at the end). For some types of texts (for example, lab reports), a Summary may have been assigned instead of an abstract. A Summary can in theory be of nearly any length (for instance, it could be a one-sentence review to start a chapter in a thesis), and it may be written by someone other than the author for a specific purpose (for instance, an assignment could require only a Summary of the methods used in several papers).
An abstract can be thought of as a special type of Summary. Abstracts are usually required to have a specific length (for instance, 1-2 paragraphs and 150–300 words), and they are almost always written by the author of the text in order to give an overview of the research and its findings.