The way I understand it, a *real* vector trace would be if you traced all the lines/shapes of a drawing in a vector graphics program and saved it in a vector format like SVG. Vector graphics have the property that you can scale them arbitrarily because they consist of mathematical descriptions of shapes, arcs, etc., not just a bunch of pixels. Apparently, some people do the tracing but then save the result as a scaled-up pixel image (e.g. in jpeg format), which defeats the entire point of vector graphics, and then mistakenly call it vector trace.