I think ICO and IEO are the same thing and the different is IEO administered by exchangers. Sometimes, if you are looking carefully, there is an ICOs from a company and want to build new project, its not a start up.
you are right, I also see ICO and IEO are the same. both are just distinguished by the way they are sold, because there is a third person who manages sales from the IEO project. in fact, most who use IEO are those who already have products and need platform development.