IEO use an exchange to collecting money from investors mate
and thats maybe the main difference between ICO and IEO,
then when the IEO done, usually the project will tradeable on the exchange as soon as possible
That's true and I think IEO is more convinient to use than to ICO because project will be more safe than to collect the fund in the site of every project. And also IEO tradable after so they have big differences.