Are these two terms describing basically the same motion, or is there a major difference in meanings of both terms?
When I see both terms I think of upstroke-downstroke, or downstroke-upstroke in rapid succession. Im not sure on sweep picking though, Im thinking the fretting hand comes into play more as far as technique goes with sweep picking. But really, who knows the best technique, and/or touch of style to explain perfect sweep picking mastery? :D