Unlike ICO the IEO is not open to the public. You must be a hosting exchange user to participate in token sales. While ICO allows contributors to buy tokens for sale by sending funds to certain addresses, an IEO requires contributors / users to buy tokens using a stock account. Compared to ICO, IEO risk is much lower for project teams and contributors. The exchange risked their credibility when carrying out the IEO, because he did not have control over the operations of the IEO project team and the product delivery as promised in the last white paper. To maintain trust with its customers, the exchange must carry out a comprehensive project assessment before launching the IEO. This provides an additional layer of protection for contributors.