The main difference is that an IPO Initial Public Offer or, basically, when a company decides to open it's capital in a stock exchange is something that is heavily regulated and watched by authorities. There are a myriad of rules and it is done in fully legal, regulated places stock exchanges. And if you have a complaint or a problem with it, you or your lawyer have a number of paths to complaint about it while your money normally still exists and it is still yours. An IPO is also done by established companies with an address, officers, bankers….
That is not to say that there are no chicanery or problems with IPOs….
The ICOs or Initial Coin Offerings are first and foremost something that is made to sound and make you think of an IPO but it has almost nothing to do with it other than the 3 letter trick to make you think it does. It is mostly not regulated, hard to control, complaint or get your money or part of it back if you happen to cross with one that it is not kosher. It is mostly a way for a newly formed company to gather capital in exchange for a promise of something. Think of it more as an extreme form of Angel investing and never as a safe investment. And they are also a way for a startup to gather cash from suck…. sorry, investors, without giving out equity. ICOs are the fad of the day for the ‘get rich quick and easy’ crowd.
I am glad to come across your explanation, it opened my enlightenment on the subject