What is the difference between the subjunctive and the optative moods in classical greek verbs?

The subjunctive mood is used to express a hypothetical situation, something that is not real (e.g. a possibility or an action that has not yet happened). The optative mood is used to express wishes and hopes (e.g. ''may''). The subjunctive mood appears in the present, past (aorist) and present perfect while the optative mood appears in the present, past (aorits), future and present perfect.