These is a specific kind of tokens issued on blockchain (usually Ethereum). The price of such a token is fixed to the rate of some other asset - it can be a stock, an exchange index, a derivative, a commodity, a forex pair, a bond, a cryptocurrency, etc. Thus, from the point of view of income from the difference in rates, it does not matter what to buy or sell - an underlying asset (for example, an Apple stock) or a token.