The difference between security tokens and other types of tokens is the fact that in the eyes of the law STOs are defined like investments and emitents of such tokens are regulated by SEC and FINMA.
According to this fact STO is more like an IPO, than ICO. One of the main advantages is a guarantee for investors. STO investor can apply for compensation on the basis of SEC and FINMA regulations, if the project fails or appears to be a scam. Security tokens are also used in case of the Simple Agreement for Future Tokens
. This agreement guarantees to investor that he/she will get a specified amount of tokens in the future.
Thus, STO is a better fundraising method for those who want to deal with classic investors. However, it is not treated as the best choice for startups at the moment. Check the data from the ICORating research on 4 Quarter of 2018