What is the difference in appearance of scalp ringworm and alopecia? can scalp ringworm appear like a normal unirriated bald patch on the scalp?

Sometimes difficult-: It can sometimes be difficult to differentiate between the two. Indeed, sometimes it can look like an unirritated bald spot. Usually you can see some scaly/crusty areas to the skin. If there is a lot of uncertainty and you really want a "for sure" answer, see a dermatologist who can do scrapings or even a biopsy to determine what is going on.