RGB works differently. With RGB you define the evolution rules at the level of Schema, but you don't restrict the future operations of the whole smart contract by introducing a global algorithm to which every state should comply. You have only local operations performed by every node and both the state and the smart contract itself are valid until each of those historical operations matches the Schema-defined rules (but again, you're not restricting all the possibilities of evolution of the history of contract with a predefined algorithm). Basically, a contract can behave very differently, until each of the changes matches certain validation rules. So it's more like local rules instead of global algorithms. Ethereum has global algorithm and you always operate the whole state of the smart contract. In RGB you operate a local portion of the state with locally applied rules, which gives you much richer range of options.