Have you ever wondered why and how the conjunctive differs in English and German?
Is there a difference?
Yes, firstly, I would say English does not have separate conjunctive verb forms like German does.
In German, we use distinct forms known as "Konjunktiv" I and II,
while English relies more on the usage of modal verbs and backshifting (a grammatical concept that occurs when reporting speech or statements made in the past. It involves shifting the tense of verbs backward to reflect the change from direct to reported, or indirect, speech).
Secondly, in German, verb placement changes are much more noticeable:
in subordinate clauses the verb is pushed to the end of the sentence.
Thirdly, in German, we use "Konjunktiv II" for polite requests.
Personally, I use it for all kind of request, even with friends.  For example, I say to a friend: "Könntest Du mir das Salz reichen". I feel this is more as related to how one was raised.
Finally, for hypothetical situations, we use Konjunktiv II: würde + inifinitive. If I had more time, I would study more German.
Wenn ich mehr Zeit hätte, würde ich mehr Deutsch lernen. 
More dramatically: Wenn ich doch nur mehr Zeit hätte, würde ich mehr Deutsch lernen.

Now comes the question for you, dear reader. When do we use 
Konjunktiv I?

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Yes, that's right. We use "Konjunktiv I" in indirect speech or reported speech. It is equivalent to the English: "He said that he had no time to learn German."
Now, try to give the German equivalent of the English sentence above. Be aware that even advanced student sometimes forget to use the beloved "Konjunktiv I":

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Er sagte, er habe keine Zeit, Deutsch zu lernen.