I am not very familiar with STO, what distinguishes it from ICO? in terms of security?
many ICOs were intended to avoid securities laws, framing their tokens as "utility tokens" to avoid the ire of the SEC. the SEC chairman later opined that virtually all ICOs he was aware of were securities under US law (including utility tokens). that led to a rebranding of ICOs as STOs (security token offerings).
STOs are affirmatively securities, granting you legal rights to shares in a company's assets or profits. they're basically like a traditional company stock that is tokenized on a decentralized platform like ethereum.
the legal standing of ICOs and their investors was always murky. STO tokens make things clearer legally, but in practice, they're basically the same thing as ICO tokens. their value depends on the efforts of a third party (the STO issuer).