An ICO is an Initial Coin Offering, while an IDO is an Initial DEX Offering. An ICO is a fundraising event where a company sells tokens to investors for funding.
An IDO is a fundraising event where a company sells tokens on a decentralized exchange (DEX) to raise funds.
The main difference between the two is that an ICO is centralized, while an IDO is decentralized. Another difference is that ICOs are often open to anyone who wants to invest, while IDOs are usually only open to accredited investors or those with invitation codes.