Utility token means it is a payment method in the ecosystem, but that won't give you any right on profit.
Security token means you have a share of the profit. Not a payment method in the ecosystem.
If that is the only difference, do you know why utility tokens were expected to be free from regulations? It does not seem utility tokens are less risky and less deserving of oversight than security tokens.
That is because they are not so seriously considered as the security tokens. Frankly, the utility tokens are just a means of safe paying for some services and that's it; you cannot earn from them.