Evidence based practice defines 'research' as the creation of new knowledge through studies or trials. (Some folks include surveys and questionnaires. See Research Types.) You could think of this as Research with a capital R.
Looking up studies and trials is defined as a 'literature review'. You could think of this as research with a small 'r'. It is what we do when we want to find out what is already known.
When practicing evidence based nursing, you usually have to perform a literature review. You seldom actually have to 'do' Research.
Evidence Based Nursing Process
Evidence based practice is answering clinical questions using a combination of information from exisiting research, your clinical expertise, your patient's values, and the local resources.
Evidence based practice can be broken down into the following steps.
You ask a question about patient care, prognosis, harm, or diagnosis.
You clarify your question using PICO (P=patient/problem I=intervention C=comparison O=outcomes).
You search for an existing answer in research studies or summaries
You evaluate the answer that you find - does it fit with your patient's values and with the resources at hand?