There is a lot to know about any given research method - too much for one page. Here are some books about research methods in UHN Library collections - you can also search OneSearch for more books, book chapters, guidelines and journal articles.
An abstract or summary of a scientific article or report that is organized or structured in well-defined sections. A typical sequence of sections includes some or all of the following: “Objectives” or “Aims,” “Design,” “Setting,” “Subjects,” “Main outcome measures,” “Results,” and “Conclusions.” The structured abstract is intended to be comprehensive and to provide a logical order for the presentation of a scientific communication. Structured abstracts are required by many journals.
Alspach JG. Writing for Publication 101: Why the Abstract Is So Important. Crit Care Nurse. 2017;37(4):12-5.
Detailed descriptions of a few patients or clinical cases (frequently, just one sick person) with an unsual disease or complication, uncommon combinations of diseases, an unusual or misleading Semiology, cause, or outcome (maybe a surprising recovery). They often are preliminary observations that are later refuted. They cannot estimate disease frequency or risk (e.g., for lack of a valid Denominator).
Rison RA. A guide to writing case reports for the Journal of Medical Case Reports and BioMed Central Research Notes. Journal of medical case reports. 2013;7:239.
A detailed analysis of the occurrence, development, and outcome of a particular problem or innovation, often over a period of time. A detailed description of a concrete situation requiring ethical analysis, judgment, and—sometimes—action
Fowler J. Writing for professional publication. Part 9: using client case studies. British journal of nursing (Mark Allen Publishing). 2011;20(5):330.
Simmons MP. Ten Simple Rules for Writing a Reply Paper. PLoS computational biology. 2015;11(10):e1004536.
The plan, or set of steps, to be followed in a study or investigation or in an intervention program.
A document prepared by a research agency for a prospective customer outlining in detail the programmes of research, its objectives, its methodology, and project timescales and costs that the agency proposes to carry out on behalf of the customer.
Guyatt G. Preparing a research protocol to improve chances for success. Journal of clinical epidemiology. 2006;59(9):893-9.
Definitions appearing in this guide are drawn from A Dictionary of Epidemiology, 5th ed. Oxford University Press.
A dictionary of epidemiology. 6th ed. edited for the International Epidemiological Association by Miquel Porta ; associate editors, Sander Greenland, John M. Last. New York: Oxford University Press; 2016.