In the context of quantum control theory, it is common to see references to both quantum control and quantum optimal control (e.g. 0910.2350 or the guide on qutip quantrum control functions). Sometimes it seems like the two terms are used interchangeably, while sometimes they are treated as different things.
For example, from the above link, it seems that quantum optimal control is (unsurprisingly) a special kind of quantum control. It is however not too clear what the exact difference is between the two. For example, are both approaches used to tackle the same classes of problems? Is the only difference in quantum optimal control theory looking for optimal solutions, while quantum control techniques have less strict requirements?