ICO collects fundraising from the website and team platform, but the IEO collects fundraising on the exchange.

so, ICO registers the coin after the token sale is complete, and the IEO registers first in the exchange. then the sale of tokens is done on the exchange.

The IEO and ICO both are the process of fundraising for a project. The proposal of ICO is presented by some team member and some some crypto promoter  form some social media. So there is a very big chance that a ico got scam cause there  is no one which can assure that a ico is not a scam. But for ieo the the exchange has a great roll in fundraising. The idea of exchange fundraising is great cause there is a good medium for verify the project. If binance launched a project that means binance verified the project. So there is a very low chance of being scammed or something. But no a day's small and medium or even exchange which is not exist trying to make IEO and may some of them came with scammers. So be careful.