Some people choose to use the label friend to highlight that regardless of how emotionally and physically close they are with said person, it is aromantic.
Others, use the label friend to highlight that despite their emotional and physical intimacy and despite the fact they feel there are romantic aspects to their relationship, they won't share practical entanglements or entwine their lives in a way that is typical of romantic relationships.
This difference is important for many people because it helps them to create expectations and fulfill expectations that is appropriate for that particular relationship. For example, I don't feel obliged to see a friend as often as I do a romantic partner, so a friend with benefits isn't in my routine weekly schedule. I don't feel disappointed or hurt by not being in theirs. If someone who is a friend needs more from me than I can offer friends, I know we are on different wavelengths and that needs to be addressed.