An operating room is a very busy place; besides surgeons there are surgical techs and surgical assistants (usually a senior surgical nurse or certified surgical tech). The surgical tech has a number of responsibilities relating to preparing the operating room and the necessary equipment as well as monitoring the patient during the procedures. Surgical assistants help the surgeon by providing surgical instruments or sponges, and/or undertaking suturing or other minor procedures as requested.
A surgical tech's main responsibility is to prepare the operating room for surgery, to check and prep the surgical instruments and equipment, and to monitor both the patient's vital signs and the operating room equipment during the procedure. Depending on the hospital, some surgical techs also prep patients and help with transporting them to and from the operating room. The surgical tech is usually the designated unsterile member of the operating room team. Most surgical tech's have at least an associate's degree, and the majority are also certified by one of two professional associations in the U.S. (CAAHEP or NCCT).
Despite the name, most surgical nurses do not work in the operating room; their main responsibilities revolve around prepping the patient immediately before surgery and taking care of them afterward (perianesthesia nurses). However, some nurses take advanced training so that they can become a circulating nurse or surgical assistant and work in the operating room. Most surgical nurses are registered nurses with four-year college or advanced degrees.
A surgical assistant is directly involved in assisting the surgeon during the procedure. Procedures include sponging, suctioning, suturing, using retractors, clamping vessels, and so forth. Both certified surgical techs and surgical nurses with advanced training work as surgical assistants.
Each hospital system has its own set of policies and job titles for the different health care professionals who work in the operating room, and often the titles and responsibilities overlap at the various institutions. However, the education and training of everyone who works in the operating room can often be inferred by the job title; you can be sure that any title involving the word "scrub" means someone who works in the sterile field, and any title involving the word "circulating" means someone who works outside the sterile field (performs unsterile prep work so others can remain sterile).