Conditional tenses are used to speculate about what could happen, what might have happened, and what we wish would happen. In English, most sentences using the conditional contain the word if. Many conditional forms in English are used in sentences that include verbs in one of the past tenses.
according to the wonderful world-wide web.
The English subjunctive is a special, relatively rare verb form that expresses something desired or imagined. We use the subjunctive mainly when talking about events that are not certain to happen. For example, we use the subjunctive when talking about events that somebody: wants to happen. anticipates will happen. --- Merriam Webster dictionary.
The Spanish routinely use the subjunctive in everyday speech; English doesn't. It often sounds archaic in English; "would that I were coming to the party! -- that's subjunctive. "Be that as it may" - that's subjunctive.