Unsold is just a term for sellers who have been selling their item at "current price" for a while, showing that they aren't successful. The word unsold is to show that the current price needs the be taken out.

"Sellers" are for people who sell below the current (and helps the suggested price). Doesn't matter how old the trade is, as long as it show the person trying to sell for less.

This is just my point of view though but some people just think sellers and unsolds are the same (technically yes but in terms, they are not).