I think the main different is that security tokens will be licensed and regulated by SEC and other financial institutions. And investors will be protected from scam. This is themain different. We have scammed many times by fake ICOs etc. So I hope security tokens will be next step in crypto and we will be able invest without risk

I think what you mean here is the different between STO and ICO, but I was talking about STO and IPO.
But about your opinion, I agree that investors will be more protected/safe with STO and there will be less risk (not without risk actually).
And if STO is a success thing in crypto, I think people will ignore ICO because they will eventually think that its just unqualified project.