Sport peppers are a very specific tiny pepper that are beloved in Chicago as an essential condiment for the classic Chi-town hot dog. They are relatively mild - more like the vinegary bite of a tiny pepperoncini than a Southwestern style pepper.

Well, a green chili pepper could be anything right? All peppers are green at some point - so I would choose based on what you need the pepper for - are you slicing or stuffing or stewing, and what's your heat tolerence? I bet they have a scoville chart somewhere there in Whole Foods!!!