Sold out or not the token/coin in IEO or ICO may not depend on the process but how the team promotes and create the concept itself. In my opinion, the difference mostly only on how the process of the IEO and ICO in crowdfunding. IEO has been listed on a certain exchange and ICO is commonly not yet. Many think that IEO will be more successful because it is listed in the exchange. But in fact, not all IEO is successful enough and they may mostly create fake trading volume.